Relationship and social factors
Relationships: A strong social support system is consistently cited as a top predictor of happiness. Close relationships with family, friends, and romantic partners provide emotional support, belonging, and shared experiences. The quality of a marriage is a very important marker for happiness in adults, according to research from the University of Chicago.
Acts of kindness: Engaging in "prosocial behavior" or kind acts for others boosts an individual's happiness and contributes to a sense of purpose.
Social connections: Interacting with casual acquaintances and fostering work friendships can also provide a happiness boost.
Community: Participation in community life and involvement in clubs or social organizations can increase well-being.

Biological and personal factors
Genetics: An individual's happiness has a strong genetic component, with some studies suggesting genes account for about 35% to 50% of the variance in happiness. A person's baseline happiness is often referred to as a "happiness set point".
Personality: Research using the "Big Five" personality traits has found that low neuroticism is the strongest predictor of life satisfaction, followed by high extraversion and conscientiousness.
Physical health: Healthy habits such as regular exercise, a balanced diet, and sufficient rest support a positive outlook and contribute to long-term well-being.
Mental health: Practices like mindfulness and learning optimistic thinking can help individuals overcome negative emotions and build resilience. Conversely, symptoms of depression and high stress are linked to lower happiness.
Age: While life satisfaction dips for some in middle age, it generally increases with age as people develop better emotional regulation skills.
Self-compassion: Higher levels of self-compassion are associated with greater positive emotions and life satisfaction among late adolescents.

Purpose and mindset factors
Meaningful purpose: Engaging in activities that align with personal values and contribute to a broader goal provides a sense of meaning and purpose. According to Seligman's PERMA model, this is a key pillar of well-being.
Engagement: Feeling a sense of "flow," where you are fully absorbed in a stimulating task, is a significant contributor to happiness.
Accomplishment: Setting and reaching goals, both small and large, is a powerful motivator that fosters a sense of pride and competence.
Gratitude: Regularly practicing gratitude, such as by keeping a journal or expressing appreciation to others, is a powerful mood booster.
Optimism: Having a hopeful and optimistic outlook is linked to higher life satisfaction.

Economic and cultural factors
Income: Financial stability and having basic needs met can substantially increase happiness. However, the effect diminishes once a certain level of comfort is achieved. Beyond this point, additional wealth does not proportionally increase happiness.
Experiences over things: Spending money on experiences, such as travel or events, tends to increase happiness more than buying material possessions.
Cultural values: The factors that predict happiness can differ between cultures. In individualistic cultures, personal achievement is a stronger predictor, while in collectivist cultures, family harmony and community well-being are more central to happiness.