Sometimes it seems like everywhere you look, there’s someone else sprouting advice about how to live a good life. Make money. Don’t focus on material things. Travel. Have friends. Go to church. Do what you love. Don’t do what you love, because then you’ll stop loving it. Apart from cat videos, needless and conflicting life advice is one thing the internet is all but guaranteed to deliver.

Fortunately, an ongoing Harvard study begun in 1938 provides some answers to life’s biggest questions, with data to back it up. The original study involved 268 male Harvard sophomores and was expanded to include include 456 residents of inner-Boston, as well as the wives and offspring of both groups. Study participants have included a U.S. president, an editor of the Washington Post, lawyers, doctors, businessman, alcoholics and schizophrenics.

Researchers found that relationships were key to a person’s long-term success and happiness. Close relationships kept people happy, and could help delay mental or physical decline. The data showed that happy relationships were better predictors of long and happy lives than factors such as genes, IQ, or social class.

Psychiatrist George Vaillant, who led the study from 1972 to 2004, wrote a book identifying the six factors that predicted healthy aging for the Harvard graduates: exercise, not abusing alcohol or drugs, having mature mechanisms to deal with life’s ups and downs, maintaining a healthy weight, and having a stable marriage. For the inner-city Boston residents, education provided a seventh factor that predicted healthy aging.

Current researchers hope to continue the study into the third and fourth generations of their original participants’ families. Longitudinal studies of this sort are notoriously difficult to conduct. They’re expensive and participants sometimes drop out. As a doctor, I sincerely hope that the Harvard longitudinal study continues for many years to come so that we can all benefit from its continued insights into human flourishing.