Robert Waldinger Knows the Secret to a Happy Life

The Harvard Study of Adult Development began in 1938 with 724 young men: 268 sophomores at Harvard and 456 boys from disadvantaged Boston neighborhoods. For nearly 90 years, researchers have followed participants through questionnaires, interviews, medical records, and increasingly sophisticated health assessments. Under Waldinger’s leadership, the study expanded beyond the original participants to include their spouses and more than 1,300 of their children, transforming it into a two-generation study of 724 families. Their children—now aging baby boomers—are helping researchers answer a new set of questions about what gets passed from one generation to the next. 

To make that possible, Waldinger also expanded the study beyond interviews and questionnaires, adding blood tests, genetic and gene-expression analyses, stress biomarkers, and MRI brain scans. The goal: to understand how relationships get “into our bodies” and shape the way we age.

Over the decades, the study set out to learn what helps people live healthy, fulfilling lives. One result kept resurfacing with unusual force: People who stayed connected to others seemed to stay healthier, too. Socially isolated people, the data revealed, “get the diseases of aging much sooner,” and one leading explanation is chronic stress, although behavioral and other biological pathways may also contribute. “Being isolated and being lonely is a stressor,” Waldinger says. Humans “evolved to have some connection with other people, probably because it was safer to be in groups”—which is “why exile was such a terrible punishment in the ancient times, because you were much more likely to die.” The pull toward others is bone-deep. “It’s wired into us,” he says, to the point that people sleep less soundly alone in a house than with someone else under the roof. It isn’t about how many friends you have; an introvert, for example, may need only a couple. But “everybody needs somebody they can count on,” he says, “particularly in times of need.”

Waldinger’s study didn’t establish this alone. A landmark 2010 meta-analysis by researcher Julianne Holt-Lunstad, pooling data from more than 300,000 people, found that strong relationships boosted survival odds by 50%—a mortality effect she later judged comparable to obesity and on the order of smoking. By 2023, the U.S. Surgeon General had declared loneliness a public health epidemic. What the Harvard study adds is unusual depth: not just that connection matters, but how it plays out across an entire human life. It was among the earliest to demonstrate a strong connection between social relationships and physical health, and Waldinger has become one of the field’s most influential public voices. His 2015 TED Talk on the power of relationships is one of the most-viewed of all time, helping bring decades of research into the mainstream. His 2023 book, The Good Life, which distilled lessons from the study, was a New York Times bestseller. “I’ve sort of brought it into plain sight,” he says.

As for his legacy, “I hope they’ll say I was a good shepherd, because I inherited a rare treasure. No study of the human lifespan has lasted this long.” 

Waldinger has taken its findings to heart. The self-described workaholic now initiates dinners with his friends and has two standing weekly phone calls with friends on his calendar. “Guys often don’t make plans with each other,” he says. “Our wives make plans for us.”

The takeaway from nearly a century of data and thousands of lives might be the ultimate longevity hack. There’s no supplement or cold plunge involved. Just connection. “Invest in other people,” Waldinger says. “Other people help you get through the hard times.”