Strong relationships with family, friends and spouses are your keys to a long, healthy and happy life. Ties with other people protect you against chronic disease, mental illness and memory decline. They are much more important for aging well than wealth or fame. Relationships with spouses are particularly important even if that partnership goes through ups and downs. People who establish strong relationships with friends outside their families also show similar patterns of benefiting from their social networks. Those who make new friends and find strong social connections after retiring are happier and healthier than people who do not.

These are the findings of a Harvard research effort that has been going on for 75 years. Do connections cause a long and happy life, or do they just reflect that healthier and happier people are more likely to form and keep relationships? Do sicker people become more isolated or immersed in bad relationships? The study’s current director, Dr. Robert Waldinger, said he is confident that strong social bonds are in fact the cause of long-term health and well-being.

Waldinger recommends some steps you can take for a life that reaps the rewards of connecting with others. Renew a relationship that’s gone stale by finding a new activity you can do with your spouse. Take long walks together or schedule date nights. Turn off your computer and go talk to people. Reconnect with family members you haven’t contacted in years and end those long-running family feuds. Lean into relationships with family, friends and your community.

The Harvard Study of Adult Development study began in Boston in the 1930s tracking 268 Harvard sophomores and eventually included research on 456 young men from Boston’s poorest neighborhoods who came from troubled homes but avoided delinquency. Waldinger, who took over in 2003 as the study’s fourth director, widened the study to include wives and children of the original subjects.

Over the course of the research, the study also has shown that the single most important thing you can do to age well physically is to avoid smoking. Another striking finding was that the primary cause of divorce among men in the study was alcohol. Alcohol abuse came before depression instead of depression leading to alcohol abuse, the study found.  The study revealed that sex remained a vital and active part of life longer for liberals than conservatives.

More than 7 million views have hit a recent TED Talk that Waldinger gave on notable findings from the long-running study. Anahad O’Connor reported on Waldinger’s Ted Talk in The Secrets to a Happy Life, From a Harvard Study for The New York Times.