When explorer and longevity investigator Dan Buettner guided me into the Costa Rican rain forest last year in preparation for an Oprah show on longevity, each of the centenarians I met there greeted me with the customary "Pura vida" — variously translated as "Pure life," "Full of life" or even "This is living!" Those are all fair ways of describing these remarkably vibrant people, who are indeed living the pure life. We'd all do well to learn their secrets.

Indeed, there's no reason we can't live to 100 — and do so with energy and good health. Here's why: longevity is not really about preventing disease. After all, getting rid of heart disease and cancer gains us, on average, less than a decade of life. And if we lived those extra years still struggling with the frailty that can make a long life less desirable, what would we have gained? No, the real goal isn't to avoid inevitable illness or breakdown. The goal is to recover from them faster and better.

Daily rigorous physical activity not only helps strengthen bones and the heart, but it also teaches balance, critical in preventing the falls that have become a leading cause of death as we age. For all the medical tests we have in our modern arsenal, the ability to exercise remains the single most powerful predictor of longevity. If you can't walk a quarter-mile in 5 minutes, your chance of dying within three years is 30% greater than that of faster walkers.

Get 15 minutes of sun every day (or take 1,000 IU of vitamin D), and take 1,000 mg of calcium. Supplement the calcium with 500 mg of magnesium to avoid constipation. All of this will help promote bone strength as you exercise. Costa Ricans get these benefits naturally: they're exposed to lots of sun between bursts of rain, which keeps their vitamin D levels high, and they drink hard, mineral-rich water and eat a traditional diet with dairy and legumes that is rich in calcium.

Choose foods that look the same when you eat them as when they come out of the ground. The powerful phytochemicals and micronutrients in whole foods (ones without food labels) support the natural rejuvenating processes of the body.

Sleep more than seven hours a day. Sleep increases your levels of growth hormone, a critical vitality booster. Half of mature Americans have difficulty sleeping, and all of them may pay a longevity penalty. Try some simple sleep hygiene like dimming the lights 15 minutes before bedtime to stimulate melatonin.

Finally, have a purpose — your family, your work, your community. There may be no better longevity booster than simply wanting to be here. You have one life; it makes sense to love living it.

Mehmet Oz is the vice chairman and a professor of surgery at Columbia University, a best-selling author and the host of the nationally syndicated television talk show The Dr. Oz Show