For two decades, Dan Buettner has studied longevity in places like Ikaria, Greece and Okinawa, Japan. While identifying the world's "Blue Zones," the five areas with the longest-living people, the researcher has studied what factors lead to prolonged lifespans.

Picking up healthy habits, even later in life, can positively affect a person's longevity, Buettner says. This is especially true when it comes to being mindful about the foods you eat.

"The average 20-year-old female could live about 10 extra years if they ate a Blue Zone type diet," Buettner says, referring to a whole-food, plant-based diet. Men, he found, could live an extra 13 years if they eat like Blue Zone residents. "Even for a 60-year-old, it's worth six extra years of life expectancy."

You don't need to wait until your golden years to start to see results. There is one key thing people in their 20s can do right now to boost their longevity, Buettner says.

If you want to live longer, bring your friends along

The best way to maintain a healthy lifestyle over time, Buettner says, is to surround yourself with people who will share it with you.

"Curate a group of friends whose idea of recreation is something active," he recommends. "Your friends are going to drive your long-term health behaviors almost more than anything."

Buettner frequently exercises with his friends, doing activities like biking and pickleball together. He says that working out as a group has also helped them develop deeper social bonds.

His habits align with centenarians like 102-year-old Deborah Szekely who takes her daily walks with a close friend and encourages people to "find friends who are active."

Buettner points out that having a healthy-eating friend in your social circle can help you make smarter food choices.

"If all your friends gather around the weenie roast or the barbecue or Pizza Hut or something like that, that's what you're going to be eating," Buettner says. "The new vegan or vegetarian friend you're going to make, that person is going to show you how to cook or show you where to get good plant-based food."

When the people around you regularly model the behavior of eating whole, plant-based foods, you're more likely to keep up the habit — and live longer as a result.

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