What makes us happy and healthy?

For more than 80 years, Harvard researchers have been following people’s lives to answer one of our biggest human questions: what truly makes us happy and healthy? The Harvard Study of Adult Development, one of the longest-running studies on human well-being, has consistently shown that it isn’t money, career success, or even physical health habits that matter most. The clearest predictor of long-term mental health and overall life satisfaction is the quality of our relationships. People who feel securely connected, supported, and understood by others are far more likely to thrive emotionally and physically than those who feel isolated or lonely.

What’s striking about the study’s findings is how powerfully relationships influence not just mood, but also resilience and even physical health. Strong, positive connections act as a buffer against stress, reduce the risk of depression and anxiety, and promote healthier lifestyle choices. On the other hand, chronic loneliness and strained relationships have been shown to increase the risk of mental health struggles, as well as physical illnesses such as heart disease and cognitive decline. Simply put: our connections shape our brains, bodies, and overall well-being across the lifespan.

For all of us, the takeaway is simple yet profound: prioritize people over productivity. Invest in friendships, nurture family bonds, and create time for meaningful conversations. Small acts—checking in on your old coworker, going to dinner with an old friend, or sending a spontaneous text to your mom, are not just “extras,” but essential steps toward lasting health. Harvard’s 80+ years of research make it very clear to us that while careers and accomplishments matter, it’s the relationships we cultivate that are the strongest predictor of a happy and healthy life.