Study: after 75 years the most fulfilling lives had one thing in common

For over 75 years, Harvard’s Grant and Glueck study has tracked the physical and emotional well-being of two populations: 456 poor men growing up in Boston from 1939 to 2014 (the Grant Study), and 268 male graduates from Harvard’s classes of 1939-1944 (the Glueck study).

Due to the length of the research period, this has required multiple generations of researchers. Since before WWII, they’ve diligently analyzed blood samples, conducted brain scans (once they became available), and pored over self-reported surveys, as well as actual interactions with these men, to compile the findings.

The conclusion? According to Robert Waldinger, director of the Harvard Study of Adult Development, one thing surpasses all the rest in terms of importance: “The clearest message that we get from this 75-year study is this: Good relationships keep us happier and healthier. Period. ”Not how much is in your 401(k). Not how many conferences you spoke at–or keynoted. Not how many blog posts you wrote or how many followers you had or how many tech companies you worked for or how much power you wielded there or how much you vested at each.

No, the biggest predictor of your happiness and fulfillment overall in life is, basically, love.

“It’s not just the number of friends you have, and it’s not whether or not you’re in a committed relationship,” says Waldinger. “It’s the quality of your close relationships that matters.”

Melanie Curtin writing in Fast Company