Evidently an author has found it by studying four communities that produce people who live into their nineties. I’m not interested in living into my nineties but I have the genes to do so (my grandma just hit ninety this year). But if I have to live to be that old, I hope that I’m strong and fit while doing it. I just joined a gym so I’m hoping to regain some of the strength I’ve lost with age (and from sitting most of the day in the car and in front of my computer and books studying for tests and writing digests):

If you are looking for a Fountain of Youth, forget pills and diet supplements. Adventurer Dan Buettner has visited four spots on the globe where people live into their 90s and 100s and outlines how they add years of good life in his new book, “The Blue Zones.”
The answer, Buettner says, includes smaller food portions, an active lifestyle and moderate drinking.
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Buettner identifies four hot spots of longevity: the mountainous Barbagia region of Sardinia, an island off the coast of Italy; the Japanese island of Okinawa; a community of Seventh-day Adventists in Loma Linda, Calif., about 60 miles east of Los Angeles; and the Nicoya Peninsula of Costa Rica, in Central America. (The term “Blue Zones” takes its name from the blue ink Belgian demographer Michel Poulain used to circle an area of long-living Sardinians on a map.)
[…]
Because of obesity and smoking, Americans are living about 10 years less than they should be, said Perls, co-author of the book “Living to 100.” He said if Americans embraced the healthy habits advocated by Buettner, the impact on public health “would be huge.”

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Limiting food intake and eating healthy also are key, Buettner said. Elderly Okinawans follow a maxim to eat only until their stomachs are 80 percent full, Buettner said. Centenarians in Sardinia, Okinawa and Nicoya rarely ate meat, and some Adventists stick only to a plant-based diet. Adventists frequently eat nuts while Okinawans eat tofu.
Drinking in moderation can help, Buettner said. Sardinians drink a dark red wine that’s loaded with antioxidants, he said.
Exposure to sun — a source of vitamin D — also is common in Blue Zones, where the residents are tan, Buettner said.