structural:expansion, linguistic:voice_change
Causes and achievement methods

Theories on how to achieve happiness include "encountering unexpected positive events", "seeing a significant other", and "basking in the acceptance and praise of others". Some others believe that happiness is not solely derived from external, momentary pleasures.

Research on positive psychology, well-being, eudaimonia and happiness, and the theories of Diener, Ryff, Keyes, and Seligmann covers a broad range of levels and topics, including "the biological, personal, relational, institutional, cultural, and global dimensions of life." The psychiatrist George Vaillant and the director of longitudinal Study of Adult Development at Harvard University Robert J. Waldinger found that those who were happiest and healthier reported strong interpersonal relationships. Research showed that adequate sleep contributes to well-being. Good mental health and good relationships contribute more to happiness than income does. In 2018, Laurie R. Santos course titled " Psychology and the Good Life" became the most popular course in the history of Yale University and was made available for free online to non-Yale students.

Some commentators focus on the difference between the hedonistic tradition of seeking pleasant and avoiding unpleasant experiences, and the eudaimonic tradition of living life in a full and deeply satisfying way. Kahneman has said that ""When you look at what people want for themselves, how they pursue their goals, they seem more driven by the search for satisfaction than the search for happiness."

Viktor Frankl, a psychiatrist and prisoner in the Nazi concentration camps during World War II, noticed that those who lost hope soon died, while those who held to meaning and purpose tended to live on. Frankl observed that joy and misery had more to do with a person's perspective and choice than with their surroundings. Three key sources of meaning that he highlights in his writings include the following:

Psychologist Robert Emmons has identified the centrality of goals in pursuing happiness. He found that when humans pursue meaningful projects and activities without primarily focusing on happiness, happiness often results as a by-product. Indicators of meaningfulness predict positive effects on life, while lack of meaning predicts negative states such as psychological distress. Emmons summarizes the four categories of meaning which have appeared throughout various studies. He proposes to call them WIST, or work, intimacy, spirituality, and transcendence.

Throughout life, one's views of happiness and what brings happiness can evolve. In early and emerging adulthood many people focus on seeking happiness through friends, objects, and money. Middle aged-adults generally transition from searching for object-based happiness to looking for happiness in money and relationships. In older adulthood, people tend to focus more on personal peace and lasting relationships (ex. children, spouse, grandchildren). Antti Kauppinen, a Swedish philosopher and phenomenological researcher, posited that the perception of time affects the change in focus throughout life. In early adulthood, most view life optimistically, looking to the future and seeing an entire life ahead of them. Those that fall into the middle life, see that life has passed behind them as well as seeing more life ahead. Those in older adulthood often see their lives as behind them. This shift in perspective causes a shift in the pursuit of happiness from more tactile, object based happiness, to social and relational based happiness.