This is a story about the NBA, a renowned Harvard study on happiness, and the key thing to think about if you're ever offered millions of dollars.

NBA fans might already know what I'm talking about. But if you don't follow the league, we can catch you up very quickly:

  • This week saw big personnel news in the NBA. The current class of free agents is one of the most talented and sought-after in memory, and dozens of players signed contracts Sunday, which was the first day they were eligible. 
  • Probably the biggest news: Kevin Durant, the 30-year-old, 10-time All-Star and former league MVP who won two NBA championships with the Golden State Warriors, signed with the Brooklyn Nets.
  • His deal with the Nets was kind of a stunner, because the Nets were barely over .500 last year, and the money and guarantee Durant got was significantly less than he was offered to play elsewhere.

Durant signed for $164 million over four years -- obviously a lot of money, but $57 million less than the $221 million over five years he could have had by staying with the Warriors.

He also spurned the New York Knicks and Los Angeles Clippers -- doubly surprising perhaps because Durant suffered an injury to his Achilles tendon during the NBA Finals this year that will actually mean he'll miss the 2019-2020 season. 

As a result, Ben Golliver of The Washington Post notes, this means he turned down (a) the most money and best shot at another championship (the Warriors), (b) the biggest platform for his off-court platform and future endeavors (the Knicks), and (c) a chance at "palm trees and a functional organization from top to bottom" (the Clippers) -- all in a single day.

So why'd he choose the Nets? Golliver has an intriguing answer. And it's the answer that the world's most successful and happiest people will understand. 

"The Nets ... ranked last in home attendance in 2018-19, held the NBA's worst record two years ago and have never won a title. Durant ... was able to look past that lack of history and visibility because he will be joined by Kyrie Irving and DeAndre Jordan, his close friends and former USA Basketball teammates."

In short, it seems like Durant is doing it because of his personal relationships. His friendships.

And while that might seem sentimental, or even short-sighted, it's also the choice that science would advise. 

I'm thinking here of the Study of Adult Development at Harvard Medical School, which tracked 724 men -- 268 Harvard graduates and 456 less-privileged men who happened to be growing up in Boston at the same time -- for going on eight decades.

Among the key findings are a simple prescription for how the most successful people ultimately find happiness. As the current head of the study, Robert J. Waldinger, famously put it:

"The lessons aren't about wealth or fame or working harder and harder. The clearest message that we get from this 75-year study is this: Good relationships keep us happier and healthier. Period."

A year ago, just before winning his second title with the Warriors, Durant gave an interview in which he explained the first half of this understanding of this phenomenon.

"After winning that championship (last season)," he told ESPN, "I learned that much hadn't changed. I thought it would fill a certain [void]. It didn't."

So now, it appears other things are bigger priorities for him: Playing for a team where he'll have a clean slate -- and playing alongside close friends.  

With his year out due to injury, we'll have to wait an entire season before we start to learn how this works out for the Nets. But it seems the odds are it will work out pretty well for Durant -- at least in terms of his personal health, happiness, and success.