In general, those who reach age one hundred in good health have stayed active or very active into old age. There are of course exceptions. If you look at centenarians, or even just within your own extended family, you will likely find someone who beat the odds: eating whatever they wanted, seldom exercising, yet making it to a ripe old age. Nir Barzilai of the Albert Einstein College of Medicine studies Ashkenazi Jewish centenarians in New York, many of whom are completely sedentary, he reports. Their longevity is likely due to genetics. Clearly genes are the most powerful factor in determining lifespan. We know this because we have identified mutations that cause a high degree of protection against age-related diseases in both mice and humans. We also know that a chimpanzee can eat the perfect diet and exercise regularly yet never come close to the average human lifespan. Despite sharing 95 percent of our DNA sequence, chimps rarely live beyond age fifty. There is nothing we can do about our genes. But after making changes in the diet, the second major factor affecting lifespan is physical activity.

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In Okinawa, I heard stories of fishermen who never retire, and I watched a woman in her nineties dance with a large bottle on her head, something she did many times a week. When she wasn’t dancing, she enjoyed playing traditional Japanese musical instruments. In Calabria, 110-year-old Salvatore Caruso told me how he walked every day to the oliveto (olive grove) and how much labor his olive trees required. In Loma Linda, the very long-lived Seventh-day Adventists are famous for their high levels of exercise, including walking fast and going to the gym. When Dan Buettner asked very long-lived Costa Ricans to share the secret to their longevity, they said they enjoyed doing physical work all their lives. When I posed the same question to the shepherds of towns with famously long-lived populations in Sardinia, they told me that every year they leave their homes around November so they can walk their sheep to lower elevations and warmer areas, where the animals can find food, and they don’t return until April or May.

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What physical activity is best for healthy longevity? The one you enjoy most, but also the one you can easily incorporate into your daily schedule and the one you can keep doing up to your hundredth birthday and beyond. Many Okinawans practice martial arts, especially a dance-inspired version of tai chi. The type of exercise you choose isn’t important. What’s important is working all your body parts with rigor—meaning to the point of breathing rapidly or sweating—for five to ten hours a week.

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I’m not talking about running weekly marathons. Overworking your body is not a good idea. If you consider the “complex systems” pillar described earlier and think about a car, why is it that no one wants to buy a five-year-old car with one hundred thousand miles on the odometer? Because despite being relatively new, it has been driven too much. You can replace the tires and repaint the chassis, but you cannot change every belt, hose, and valve, and there’s a high chance that some overworked component will break down. On the other hand, you don’t want to leave your car parked in the garage most of the time, as this will also eventually cause it to break down.

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The same holds true for the human body. It’s important to exercise, but not to overexercise, because knees, hips, and joints will eventually get damaged—particularly if you continue to exercise when you feel pain. On the bright side, certain exercises and diet can cause tissue to self-repair and regenerate, so the human body has built-in advantages over a car.

Optimizing Exercise for Longevity

The following guidelines are for exercising to maximize health and longevity:

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Walk fast for an hour every day. The goal of walking for an hour a day can easily be achieved. For example, pick a coffee shop or restaurant fifteen minutes from your work and make a point of going there twice a day. It can also be achieved on the weekend by walking when you would normally drive. Every year, I take my USC students from Los Angeles to Genoa, Italy, for three weeks. On the first day, we do a walking tour of the city. I then urge them to continue walking everywhere for the duration of the trip. By the end of the course, they are used to walking around the city and realize that they enjoy it and feel better in general.

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Ride, run, or swim thirty to forty minutes every other day, plus two hours on the weekend. The best way to achieve this goal is to have both a stationary bike and a road bike. When you can, ride outside; when you can’t, use the exercise bike in high gear (use a bike that provides the option of high magnetic resistance, which makes it hard to pedal—as if you were going uphill). After ten minutes, you should be sweating. If you ride on the street, go uphill for at least ten to fifteen minutes. Do this for about forty minutes every other day and for two hours on the weekend.

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Bicycling may be healthier than running because it minimizes stress on the joints. However, a long-term study showed that long-distance running among healthy older adults was not associated with osteoarthritis, so an injury caused by long-distance running may be less common than we would expect. In fact, another study that followed 74,752 runners for seven years concluded that running reduced both weight and the risk of osteoarthritis.

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Following one pillar of longevity (studies of complex systems), we could conclude that bicycling is preferable to running. But following another pillar (epidemiology), running would appear to be equally good. Its beneficial effects, however, may change over time and may vary in individuals who are injured, have joint damage, and continue to run. Thus, I would recommend a bicycle as a first choice, but running is also fine if the limits described below are followed. Swimming is another excellent form of exercise, although its beneficial effects on longevity have received less scrutiny than those of running.

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Use your muscles. Humans evolved as a species that walks, runs, climbs trees and hills, and uses a variety of muscles all the time. Now people use elevators and escalators instead of stairs, drive instead of walk, use dishwashers and washing machines instead of washing dishes and clothes by hand, buy food instead of growing it, and hire people to do even minor repair work around the house instead of fixing things ourselves.

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Every muscle of the body needs to be used frequently, because muscles grow and maintain or gain strength only in response to being challenged. Climbing six flights of stairs rapidly can cause leg pain, especially if you haven’t done it in a long time. That pain is evidence of minor injury to your muscles. In the presence of sufficient amounts of proteins, muscle injury leads to the activation of “muscle satellite cells” and, eventually, to muscle growth. Muscles can be slightly injured and rebuilt by doing simple everyday tasks that are challenging. Of course, minor injury can turn into major injury if the burden in weight-bearing exercise is too high or if you keep reinjuring already inflamed muscle or cartilage. Muscle training must be balanced to avoid both acute injuries and the slow, chronic damage that comes with ignoring pain and continuing to put stress on an injured joint.

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This excerpt was reprinted from THE LONGEVITY DIET in arrangement with Avery, a member of Penguin Group (USA) LLC, A Penguin Random House Company. Copyright © 2018, Valter Longo.