For 86 years, researchers at Harvard have been studying the lives of hundreds of people and their families to discover what makes us happy.
For example, the Harvard Study of Adult Development found that happy people tend to have good conflict-resolution skills, exercise often and maintain positive relationships.
Dr. Robert Waldinger, the study's director and a professor of psychiatry at Harvard Medical School, recently appeared on Simon Sinek's "A Bit of Optimism" podcast.
When asked what the happiest people "get right" as teens and young adults, Waldinger said they "care about making a difference in the world, and they care about the world."
Even if their purpose changes, "the people who stay with that aspiration, I think stay engaged in life. And I think that's what they get right," he added.
This aligns with what longevity researchers and happiness experts say about the importance of having a purpose for life satisfaction and wellbeing. Waldinger points to psychoanalyst Erik Erikson's concept of generativity versus stagnation in adult development.
"Generativity [is] wanting to be part of something bigger than yourself," Waldinger explained. "Realizing, 'Oh I want to help raise kids' or 'I want to mentor people' or 'I want to do something that's not just [about] me.'"
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Stagnation is the opposite and involves feeling stuck in life and struggling to find a sense of meaning.
The people who choose generativity over stagnation, especially throughout the different stages of their lives, "become the people who are going to look back on their lives with less regret, with more of a sense that my life was good enough," Waldinger said.
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