The recipe for Happiness: A critical review-introduction to a new theoretical model and a new psychometric tool for the measurement of Eudemonia

eudemonia, critical review, happiness, interpersonal relationships, measurement, Psychological Equilibrium Model (PEM), psychometric tool, self-acceptance, self-knowledge, psychological well-being This critical review refers (a) to all scientific knowledge to date on the subject of Happiness and (b) to the creation of a new prototype psychometric tool, for its measurement. A new model for the development and increase of happiness levels, the Psychological Equilibrium Model (PEM), is proposed. The Psychological Equilibrium Model (PEM) aims to examine the factors of Happiness and contribute to a more comprehensive approach of the concept. According to the Psychological Equilibrium Model (PEM), Happiness is defined as the psychological result of growth in four areas. In particular, if a person experiences (a) high levels of selfacceptance, (b) positive relationships with family and (c) friends, and (d) is able to set goals and plans for the future, he or she will experience higher levels of Happiness. The main objective of this new model is to measure the objective factors and personal characteristics that make it easier for people to achieve and maintain optimal happiness. This may lead to the creation of a new psychometric tool for the objective measurement of happiness based on the Psychological Equilibrium Model. The purpose of the article is to help define the notion of Happiness in a new more comprehensive and holistic way. CONTACT

eudemonia, critical review, happiness, interpersonal relationships, measurement, Psychological Equilibrium Model (PEM), psychometric tool, self-acceptance, self-knowledge, psychological well-being This critical review refers (a) to all scientific knowledge to date on the subject of Happiness and (b) to the creation of a new prototype psychometric tool, for its measurement. A new model for the development and increase of happiness levels, the Psychological Equilibrium Model (PEM), is proposed. The Psychological Equilibrium Model (PEM) aims to examine the factors of Happiness and contribute to a more comprehensive approach of the concept. According to the Psychological Equilibrium Model (PEM), Happiness is defined as the psychological result of growth in four areas. In particular, if a person experiences (a) high levels of selfacceptance, (b) positive relationships with family and (c) friends, and (d) is able to set goals and plans for the future, he or she will experience higher levels of Happiness. The main objective of this new model is to measure the objective factors and personal characteristics that make it easier for people to achieve and maintain optimal happiness. This may lead to the creation of a new psychometric tool for the objective measurement of happiness based on the Psychological Equilibrium Model. The purpose of the article is to help define the notion of Happiness in a new more comprehensive and holistic way.
In 1989, Carol Ryff, based on the previous theories of Maslow, Rogers, Allport, Jung, Jahoda, Frankl, Erikson, Buhler and Neugarten, suggested a multidimensional model for measuring happiness, in order to create a strong theoretical base that treats the variable as a crucial and basic component of positive human functioning and positive health (Ryff, 1989). This model consists of 6 psychological aspects in which humans may thrive and function in the most positive way. The six aspects of psychological wellbeing are self-acceptance (the knowledge and acceptance of oneself, including the awareness of one's limitations), purpose in life (finding meaning and direction in life despite challenging circumstances), positive relations with others (deeply connecting and maintaining this connection with significant others), environmental mastery (the skill of efficiently managing life situations and shaping the environment according to one's needs), autonomy (being self-determined and living according to one's authentic way) and personal growth (using one's talents and unique capacities). According to this theory, a human being is continually trying to improve all of the above aspects, in order to reach a eudemonic way of living. These six aspects are the basic components of psychological well-being and the essential features of positive human functioning, which individuals are trying to increase during their life (Baumeister, 1991). Nevertheless, we tend to approach happiness through its relative emotions (Carver & Scheier, 1990) and not via the prerequisites that form its foundation (Clarke et. al. 2000). The purpose of this article is to present traditional ways to approach happiness and propose a new model that may solve previous models' flaws.

The ingredients of Happiness
More analytically, self-acceptance is one of the basic characteristics of mental health, self-actualization, optimal functioning, and maturity (Ryff, 1989). Self-knowledge, which is a core factor of self-acceptance, creates a positive attitude towards oneself and a positive image of oneself (Diener, 2009). A human being, who has goals, intentions, and a direction in life, functions positively and has the feeling of a meaningful life (Ryff, 1989). Goals, intentions, and direction in life are included in the aspect of purpose in life, a dimension that seems to distinguish and can offer protection in physical health (Deiner & Seligman, 2002). Purpose in life might be a strong motivation to learn from negative experiences and reevaluate them in order to gain new capacities and manners and quickly refocus on one's goals and purpose (Schaefer et al, 2013). Additionally, purpose in life might be a resource, which can be used to cope with difficult situations, handling of these situations, balancing the effect of adverse experiences, and finally facilitating the learning process, while developing greater emotion regulation skills over time (Schaefer et al, 2013).
Purposeful life engagement has also been increasingly linked to better health outcomes, including assessments of morbidity and mortality (Dillon et al., 1985). Findings support that purpose in life is a protective factor for health, and more specifically higher levels of purpose in life can reduce the risk of a stroke in older adults (Kim et al., 2013), reduce the risk of myocardial infarction in heart disease patients (Kim et al., 2012), predict lower levels of allostatic load (Zilioli et al., 2015), provide better cognitive function in patients with Alzheimer (Boyle et al., 2012), raise the odds of using preventive health services (Kim et al., 2014) and promote longevity in older adults (Dykman, 1998;Hill & Turiano, 2014). Impaired levels of purpose seem to be independent of the presence of psychopathology and these results agree with the existent concept of positive psychology that the presence of well-being does not simply correspond to the absence of disease and vice versa (Tomba & Tecuta, 2016). Optimal human functioning does not refer to the absence of disease or infirmity (Frijda, 1999). Instead, it refers to the 192 stage beyond neutral in which the human being functions in an optimal way, biologically, mentally, psychologically, and socially (Kimiecik, 2011).
Positive relations refer to the ability to love and be loved and it is considered as a basic feature of mental health. Individuals with a higher sense of self-actualization are more likely to feel empathy and affection for all human beings and at the same time experience deeper levels of love and friendship (Ryff, 1989). Being able to create, develop, and maintain close relationships with others is a crucial aspect of psychological well-being and an example of maturity, according to developmental theories (Li et al., 1999). The concept of positive relations not only refers to the close relations with family and friends but also includes the capacity of an individual for identification with others on a social level. Being able to identify with others means you are able to belong in a larger group, the broader society, and explore your developmental capabilities inside the security that this group offers (Lyubomirsky et al., 2004). So, positive relations refer to two dimensions (personal and social), which have a bidirectional relation as one promotes the other (Lyubomirsky et al., 2004).
At this point, it is important to note that if people are living according to their demon this doesn't mean that they don't experience stressful situations but they use their inner resources of subjective vitality that push them to choose behaviours helpful to revisit their feel of eudemonia (Klug et al., 2002). One of these behaviours is taking care of one's self. Health -promotion behaviours are more likely to be used by those who have higher levels of life purpose and positive relations with others (Ryff & Singer, 1998a). Healthy behaviours include engagement with life and self and participate in optimal functioning: "taking good care of yourself presupposes that your life is worth taking care of" (Ryff & Singer, 1998b).
Data from previous research suggest that a strong feeling of purpose in life can increase healthy behaviours, such as the use of preventive health services (Kim et al., 2014). Furthermore, higher levels of psychological well-being promote physical exercise on a frequent base and especially the aspect of selfacceptance seems to be a strong predictor of engaging in physical activities (Garcia et al., 2012). Based on the existing literature for the relationship between physical exercise and psychological well-being, previous results showed that when we enhance physical activity, we can improve the general well-being of an individual (Lyubomirsky et al., 2004). That suggests that this relationship might be bidirectional, and physical activity can be an appropriate strategy to increase well-being (Mack et al., 2012). Kagee and Dixon (2000) propose that when someone is choosing a healthy behaviour on a regular basis, he is expressing the concept of self-actualization and maximizes his personal fulfilment (Kagee & Dixon, 2000).
The aspect of environmental mastery is highly connected with creativity, in the notion that a human being, who can master his environment according to his needs, practically uses new and creative ways, through his physical and mental activities, in order to control external situations and take advantage of environmental opportunities (Ryff, 1989). This aspect includes the active participation of an individual in all aspects of life: you have to engage with the environment in order to change it. Active participation and environmental mastery are basic components of positive psychological functioning (Ryff, 1989). Furthermore, environmental mastery seems to be a part of positive ageing. Being able to maintain a higher level of psychological well-being in the face of the changes and losses of later life is generally considered a basic part of "healthy" ageing (Baltes & Baltes, 1990;Rowe & Kahn, 1998). One of the most influential definitions of positive ageing consists of three elements: absence of physical illness or disability, high levels of cognitive and physical functioning, and active engagement with life (Rowe & Kahn, 1998).
Autonomy is highly connected with motivation and self-determination theories (Lyubomirsky & Tucker, 2000). An autonomous person is able to decide for his own sake and be guided only from internal motives (Myers & Diener, 1995). An individual with the ability of autonomous functioning is described as having an internal locus of control (Ryan et al., 2008). Moreover, he or she has the ability to evaluate oneself by personal standards, and that gives him/her a sense of freedom from the typical norms (Ryff, 1982(Ryff, , 1989(Ryff, , 2012a(Ryff, , 2012b(Ryff, , 2014a(Ryff, , 2014b. The dimension of autonomy is the basic component of another theory for eudemonic well-being, the Self-Determination Theory (SDT -developed by Deci & Ryan, 1985), which suggests that when the personal needs for autonomy, competence and relatedness are satisfied, motivation and well-being are enhanced . Likewise, if the above needs are not met, there is a significant negative impact on our well-functioning (Deci & Ryan, 1985). In this concept, the theory of Csikszentmihalyi about Autotelic Personality is also under the field of psychological well-being. Autotelic people are those who often engage in activities for their own sake, and experience flow states frequently (Csikszentmihalyi, 1999). Another scholar of the topic, Seligman (2002), suggests that both pursuits of engagement/flow and meaning can be considered eudemonic (Seligman, 2002).
The last dimension of psychological well-being theory is the dimension of personal growth (Ryff & Singer, 2008). Personal growth seems to be the concept that is closest to Aristotle's idea of eudemonia and that is because it refers to a continuous development and flourishing of one's unique talents and skills, which Aristotle's means by the world "demon". In fact, "demon" refers to the unique talents and capacities of a human being, which one has to find, create, and develop, in order to fulfil his/her unique life goal. The two basics components of eudemonia are self-knowledge and fulfilling your true potential. Aristotle believed that every living creature has a special goal to fulfil in life and, therefore, everyone needs to find their true purpose and live according to it . In order to achieve optimal psychological functioning, we need to grow and expand our capacities, during lifespan (Seligman & Csikszentmihaly, 2000). It is clear that personal growth refers to the capacity of a human being to transform and flourish in an unstoppable way and helps individuals to cope with new challenges or tasks at different periods of life (Ryff, 1989(Ryff, , 2002. The upper mentioned model depicts a synthesis of existing Happiness Models and has been selected in order to provide a panoramic view of existing literature. Most existing models agree that all of the above are parts of the notion of Happiness.

The measurement of Happiness
This multidimensional model of measuring Ηappiness established the concept of eudemonia as a main aspect of psychological well-being and these six aspects became central criteria for predicting psychological well-being (Ryff, 1989). Ryff's Scale of Psychological Well-being (Scale of Psychological Well-being [SPWB], 1989) was created and the concept of eudemonia started to gain a solid theoretical ground as a main aspect of positive human functioning. Meanwhile, eudemonic well-being is finally distinguished from hedonic well-being (life satisfaction and pleasure), and despite both of them include positive functioning, eudemonic well-being, and purposeful life can empower the organism when striving with life adversities (Sheldon & Kasser, 1995. Psychological well-being is highly correlated with the existential challenges of life (Ryff, 2002), such as the human striving for a meaningful and responsible life, even in difficult conditions (Stone et al., 1994). Existential philosophies are deeply connected with the sense of eudemonic well-being, and especially with purpose in life, as they both try to understand the process of full growth and development of a human being . It is important to state that the notion of Happiness is based on a deeply subjective emotion and it is the result of personal subjective cognitive appraisal and decision. This element is characteristic of the difficulty to successfully and accurately measure its levels in individuals (Wong & Fry, 1998).
Studies have examined socio-demographic variables (age, gender, and education) in the dimensions of Psychological Well-Being (Clarke et al., 2000;Keyes & Ryff, 1998;Marmot et al., 1997;Ryff & Keyes, 1995; Ryff & Singer, 1996 and have connected Psychological Well-Being with life transitions and experiences such as parenthood , community relocation (Kling et al., 1997a;Kling et al., 1997b;Smider et al., 1996), and health changes of later life (Heidrich & Ryff, 1993). Psychological wellbeing was also related to resilience Singer et al., 1998). In addition, psychological wellbeing scales were used to examine well-being outcomes to diverse life challenges such as body consciousness (McKinley, 1999), work aspirations and achievements (Carr, 1997), marital status change (Marks & Lambert, 1998), caregiving (Li et al., 1999, recovery from depression (Fava et al., 1998) and personal projects (McGregor & Little, 1998). Studies have shown that optimal well-being is deeply connected with age and education and that midlife and older adults who had higher levels of education were most likely to flourish in life and have high perceived quality of life (Ryff, 2002). Additionally, age and education seem to have a positive association with psychological well-being and predict higher levels of well-being. Younger age was associated with higher psychological well-being and optimal experience. Similarly, university education predicted higher psychological well-being, optimal experience, and hedonic balance (Bassi et al., 2013). Furthermore, data suggests that a persistently high well-being level can be protective for health outcomes of educationally disadvantaged individuals known to have greater risks of subsequent health decline (Ryff et al., 2015).

Results of experiencing Happiness
In the last two decades, there is a flourishing ground in the field of research that correlates psychological well-being and health. This shift, which has been observed in the last two decades, is due to the recognition that psychology had focused mostly on human pain and suffering, and too little on human happiness and positive functioning (Ryff, 1989). Researchers started to point out that psychological wellbeing can influence quality of life, health behaviours and physical health . Furthermore, , in their research with older women, point out the fact that women with higher levels of psychological well-being had lower levels of daily salivary cortisol, pro-inflammatory Cytokines, cardiovascular risk and longer duration of REM sleep . They also came to the conclusion that when the individual lives in an authentic way towards himself, he focuses on what is "intrinsically worthwhile" and that can lead to vitality and self-determination, which increase intrinsic motivations for new challenges, exploration, and learning (Ryan & Deci, 2001). Psychological well-being is the balance between internal motivation (true self) and external circumstances (environment), that leads to an authentic expression of self, vitality, and the sense of aliveness (Ryan & Deci, 2001).
Based on a recent literature review (Boufali-Bavella et al., 2017) results showed that individuals with higher levels of happiness had a lower risk of mortality or mobility disability (Zaslavsky et al., 2014), better health status during a period of 10 years (Ryff et al., 2015) and lower risk of frailty incidence (Andrew et al., 2012). Other data have shown a significant association between happiness and risk of prefrailty, and also that men and women with higher levels of psychological well-being are less likely to become frail over a 4-year follow-up period (Gale et al., 2014).
In addition, findings (Boufali-Bavella et al., 2017) proposed that higher levels of happiness were associated with reduced CTRA gene expression, which is responsible for increased inflammation genes expression and decreased expression of antiviral and antibody genes (Fredrickson et al., 2015;Fredrickson et al., 2013).
Biology, psychological well-being, and health seem to have an important interaction, and psychological well-being offers protective benefits that lead to better biological regulation and more positive disease results (Ryff, 2013). In addition, research suggests (Boufali-Bavella et al., 2017) that happiness is linked with specific neurobiological mechanisms, through which it may improve physical health. Increased levels of happiness were connected with sustained engagement of striatal and dorsolateral prefrontal cortex, which is also responsible for lower levels of cortisol (Boufali-Bavella et al., 2017). Striatal is linked with the reward system and working memory. Cortisol protects the organism from several diseases such as osteoporosis, and it is responsible for insulin production, wound healing, and electrolyte balance. It is important to note that these findings support the concept that happiness may act as a moderator of the physiological and biological systems (Ryff, 2014a). On this note, data suggests that eudemonic well-being is also closely associated with grey matter volume of insular cortex volume (Lewis et al., 2013). Specifically, happiness has been positively associated with one's grey matter volume of the right insular cortex. Purpose in life, positive relations, and personal growth scores showed positive correlations with right insular cortex volume. Positive relations also showed a significant association with left insular volume (Lewis et al., 2013).
These results show the important links between happiness and brain structure affecting physical health and may suggest that insular cortex accommodates happiness by producing the necessary capabilities to successfully managing exterior circumstances. These findings provide evidence of individual differences in the brain structure and link an important psychosocial trait with mental and physical health (Lewis et al., 2013). The importance of linking biology and happiness refers to the fact that well-being can gain a solid theoretical base as an internal way to flourish and function at optimal levels.
The linking of happiness with neurobiological mechanisms and specific genes expression, increase the concept that eudemonia is the right way to live and it might also be an alternative way to encounter physical illness and modify the existing medical models .
Findings (Boufali-Bavella et al., 2017), confirm that happiness is a basic component of healthy ageing, it can be a protective factor against diseases and disorders, it promotes longevity, prevents better outcomes for specific diseases and enhances healthy behaviours.

The ingredients of Happiness -Proposed Model of Psychological Equilibrium (PEM)
After a systematic review of previous research (Boufali-Bavella et al., 2017), we have indications that there is a stage of preparation before a human being can experience happiness and well-being. This preparative stage may be the Psychological Equilibrium stage (Boufali-Bavella et al., 2017) and according to our Psychological Equilibrium Model, we have approached Happiness as the result of significant performance in four fields. This systematic review of happiness serves as a psychometric basis for the development of our model and the prototype psychometric tool we are introducing. Before explaining in a more analytical way these four fields, it is crucial to note the basic limitation in the measurement of psychological well-being and happiness so far, which is the exclusive use of self-report measures. Their main disadvantage is that they force us to rely solely on subjective estimations of participants regarding their happiness levels, even though sometimes they lack knowledge as to what happiness consists of while at the same time their answers might be biased by following political correctness and social desirability tendencies. This phenomenon often leads to measures that lack reliability and validity. In order to cope with this problem, we are proposing a Psychological Equilibrium theoretical Model which measures the intensity of each field based on real-life characteristics.
The four fields that have been associated with Psychological Equilibrium and Happiness (Galanakis & Stalikas, 2019) are the following: 1. Self-Acceptance / Positive Relationship with our self. This dimension evaluates the degree in which the person knows itself and can regulate its emotions. It depends on variables such as selfesteem, self-image, skills, talents, satisfaction with oneself, major life accomplishments, major negative and positive life events, personal role in society, potential, opportunities, and threats. 2. Interpersonal relationships. This dimension focuses on the quality of relationships with friends, colleagues, acquaintances, as well as the quality of personal and sexual relationships. It also focuses on problems regarding socialization, loneliness, and superficial relationships. It reflects personal levels of emotional and social support regarding meaningful others. 3. Family. This dimension focuses on the quality of relationships between family members. It also deals with the variety of emotions emerging from family interaction, compatibility among family members, family history, and problematic situations regarding family matters. The notion of family relations and its quality refers to all new formulations and concepts of family that may be different from the traditional approach to the institution. Family is not only blood relations but mainly what the person defines as family based on the qualities of the relationship and the role of the members. 4. Future goals. This dimension focuses on whether the person has established goals for the future in a variety of fields career-wise, travel wise, personal life, expectations, aspirations and dreams. The upper mentioned four factors as depicted in Figure 2 have also emerged from 2000 personal interviews with adults in Northern Greece. Happiness stems from the above four fields. If a person experiences a satisfying relationship with oneself, has self-esteem, uses his unique talents and skills, has deep interpersonal relationships with significant others and family, and finally, has a specific direction in life, he or she will experience high levels of happiness. These four axes appear to synthesize the theoretical basis of the model.
The Psychological Equilibrium Model aims to understand in a deeper way the concept of happiness and psychological well-being and investigate what really makes humans able or not able, to experience eudemonia and happiness. Α basic goal of this critical review is the further development of research in the field of psychological health and positive human functioning. We aim to create a prototype psychometric tool that will aid us to better understand the phenomenon of happiness and psychological well-being, in order to design targeted interventions and psycho-educational programs, aiming to develop, increase and establish the basic features that facilitate the state of psychological health. This prototype psychometric tool will help us, and the wider scientific community, to investigate a complex concept of human optimal functioning, which is already connected with positive psychology variables such as mindfulness, self-compassion, positive emotions, positivity, optimism, meaning of life, hope, faith, psychological resilience, companionship, social support, and emotional intelligence, in terms of objective aspects of everyday life. The Psychological Equilibrium Model Scale (PEMS) will constitute an extension and evolution of the already existing research and our goal is to provide evidence for the pursuit of happiness and psychological well-being. Our expectation is that the PEMS will expand our knowledge on those two concepts and at the same time will establish a new conceptual framework in order to facilitate new applications of the model and further research projects.
This prototype tool will also solve existing limitations of self-report measurement, as it approaches happiness and psychological well-being, by measuring in an objective way, the intensity of the four aspects of the Psychological Equilibrium Model. This seems to be the basic problem of existing psychometric tools on happiness. Furthermore, this tool will be able to illuminate the unclear concept of why some people are happier than others and why people who are expected to score lower in the psychological well-being scales, finally do not. In a recent study (Bassi et al., 2013), which examined the levels of happiness in people with multiple sclerosis, their caregivers and their health professionals, results showed that the caregivers of persons with multiple sclerosis reported low levels of happiness, same as the people who were suffering from the disease. Based on previous research and existing literature (Boufali-Bavella et al., 2017), we came to conclude that it has to be a previous stage, including specific characteristics, which facilitates the presence of happiness. And, if this stage is not well established, none intervention can be beneficial for a long-time period. Maybe this stage is the Psychological Equilibrium stage that future research can empirically validate (Galanakis & Stalikas, 2019).
Measuring and examining the concept of psychological balance in difficult circumstances is a key point of the core of eudemonia and psychological well-being. If we take under consideration what is mentioned above, people living according to their demon doesn't mean that they don't experience stressful situations but they use their inner resources of subjective vitality to push them to choose http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 17/05/2021 07:33:20 | behaviours helpful to revisit their feel of eudemonia (Klug et al., 2002). Positive functioning and psychological balance do not prerequisite external balance or social prosperity. Conversely, psychological balance, and health are probably what keep people alive and fully functional in adverse conditions.
The concepts of happiness and its related aspects (well-being, eudemonia, prosperity) have not yet been fully understood and described in the scientific community. Their complexity and the selfreferencing tools used in their research do not allow us to reveal their deeper contribution to psychological health. It is difficult to have a definition of these concepts because of their unique importance to each of us. The most common definition of happiness is in terms of frequent positive affect, high satisfaction with life, and rare negative experiences. Our aim is to eliminate this constraint and measure levels of psychological happiness with an objective psychometric tool based on the psychological balance model that measures the intensity of each aspect (self-acceptance, interpersonal relationships, family relationships, and future goals) about the real characteristics. We support the fact that all individuals are able to experience aspects of happiness if they have reached a psychological equilibrium phase.

Discussion
Literature suggests that happy people are more likely to achieve greater self-control, self-regulation and coping abilities (Aspinwall, 1998;Fredrickson & Joiner, 2002;Keltner & Bonanno, 1997), enhanced immune system (Dillon et al., 1985), and even to live a longer life (Danner et al., 2001;Ostir et al., 2000). Also, happy people are not just self-centered or selfish. Literature suggests that happy people tend to be more cooperative, philosophical, altruistic, and tend to help their fellow human beings. (Isen, 1970;Kasser & Ryan, 1996;Williams & Shiaw, 1999) Although the sources of personal happiness may differ (Lyubomirsky, 2001;Lyubomirsky & Lepper, 1999), in almost every culture, people classify the pursuit of happiness as one of the most worthwhile goals in life (Diener & Oishi, 2000;Diener et al., 1995;Freedman, 1978; Triandis et al., 1990. Moreover, the positive effects of happiness seem to benefit not only individuals but families, communities, and societies (Myers, 1992;Veenhoven, 1988). However, little is known about the sources of individual differences in adult happiness and why some people manage to maintain happiness, while others are constantly oriented towards misery (Lyubomirsky, 2001).
In the area of happiness, very few intervention studies have been carried out. In fact, researchers are still surprisingly little awareness of how to increase happiness and help people become happier (Lyubomirsky et al., 2005). An important reason for this neglected area is scientific pessimism about whether increases in happiness can actually occur. Fortunately, there is a shift in this concept and a more optimistic viewpoint has been found in the scientific field, providing evidence that happiness can and should be increased (Lyubomirsky et al., 2005).
The results from previous surveys show that older people are happier than younger (Charles et al., 2001;Diener & Suh, 1998; Roberts & Chapman, 2000; Sheldon & Kasser, 2001. These data confirm the view that happiness can be achieved over time and more importantly not only by some people but perhaps by their majority (Lyubomirsky et al., 2005).
Another theoretical perception of happiness refers to the fact that if we influence the types of experiences and environments we have or seek to have, we can expect increased levels of happiness (Lyubomirsky et al., 2005). Researchers looked at the objective determinants of happiness in Western cultures and the extent to which happiness relates to environmental aspects and demographic factors such as age and gender. According to this objective view, happy people are the ones who have the most advantages in everyday life, for example, a comfortable income or a supportive marriage. However, the general conclusion from almost a century of research on the determinants of happiness is that objective circumstances, demographic variables and life events are associated with the variable less strongly than expected and complementary evidence suggests that they cannot secure happiness or life satisfaction (Diener et al., 1999;Lyubomirsky & Ross, 1997). Circumstances, demographic variables, and life events do not account for more than 8% to 15% of the variance in levels of happiness (Andrews & Withey, 1976; Argyle, 1999Diener, 1984).
Still, the question of the ability or not to increase happiness remains, where some theoretical perspectives show that happiness can increase, and other theories imply that it cannot. In addition, a critical question to be answered is what circumstances, activities or habits are most likely to bring benefits that can be maintained in order to increase happiness (Lyubomirsky et al., 2005). These elements are crucial and must serve as a theoretical basis for the development of new psychometric tools in the field of Positive Psychology.
Happiness is mostly a subjective experience that everyone defines in an exclusive and unique way. However, as Lyubomirsky (2005) points out: "The fact that the view of happiness is necessarily subjective does not mean that the influences on this view cannot be studied empirically." (Larsen & Fredrickson, 1999;Schwarz & Strack, 1999). In addition, Lyubomirsky (2005) adds a key point to the measurement of happiness suggesting that even if the appreciation of happiness is subjective, it does not necessarily mean that it is not related to relatively more "objective" variables.
In addition, another question about happiness needs to be answered: the question of how a person could take appropriate steps to "pursue" happiness. We have reasons to believe and, potentially, in the future, to investigate that it is possible to become happier if the four aspects of psychological equilibrium are growing and expanding. Based on the existing literature, it is already known that a change in deliberate activities can provide a potential for enhancing happiness. However, it is not yet clear how to maintain and expand this strengthening potential. We also know that happiness can increase but the data show that this will not last, mainly due to the hedonistic adaptation, which tends to move people back to their starting point after any positive change (Lyubomirsky et al., 2005). After a long period of research, we have come to another conclusion, which suggests that it is not the hedonic adaptation that reflects levels of happiness, but rather the level of psychological equilibrium that it has not yet been conquered.
Moreover, data show that wealth and health variables have little psychological effect on the wellbeing of people. Conversely, a series of psychological processes are required to alternate the effects of stressful events, living conditions, and demographic factors on levels of happiness (Lyubomirsky, 2001). We currently are on the way to collect valid evidence, based mostly on bibliographic research, that individuals experiencing higher levels in the four aspects of the psychological equilibrium model will be more able to mitigate the interpretation of unfavorable living conditions and at the same time maintain their high level of happiness. These data will serve as the conceptual basis of our model and will help us validate the psychometric qualities of the psychometric tool.