The 5 places with the world's longest-living people all have this in common: 'It seems to make us happier'

After 20 years of interviewing centenarians and visiting "Blue Zones," the areas in the world where people tend to live the longest, Dan Buettner learned something that he didn't expect.

"When you take worldwide data on happiness, and you control for everything else, you find that people who live next to water are...happier than people who [don't]," Buettner says.

In fact, all five Blue Zones — Okinawa, Japan; Sardinia, Italy; Loma Linda, Calif., U.S.; Ikaria, Greece; Nicoya, Costa Rica — are on the water.

While there are various theories about why this is the case, the end result is clear.

"It may be the tranquilizing effect of water or it may be that the climate is moderated because of the water," Buettner says. "But it seems to make us happier."

And happiness isn't the only positive side-effect of living by the water. A 2017 systematic review published in BMJ Open found that spending time near coasts, lakes or rivers can "promote health and well-being and prevent disease."

Buettner himself lives in Miami Beach, and says geography plays a big factor in his well-being. But it's "not so much about the water, per se," he says. Instead, he credits the appealing location and weather with helping him live a healthy lifestyle.

"I'm looking at the ocean right now, where I swim every day, and the beach on which I walk every day," he tells Make It. "I've intentionally chosen a place where it's very easy and enticing to get physical activity all year long without really trying."

He aims for daily movement doing activities he enjoys, including stand-up paddle surfing, or lower-intensity exercises like walking.

"The key is not intense physical activity — 'no pain, no gain.' The opposite is true," Buettner says. "When there's no pain,