(FORTUNE Magazine) – FIRST, a brief disclaimer from one of the country's top experts on aging. ''Life's a crapshoot,'' says the NIA's Dick Sprott. ''There aren't any guarantees.'' The odds get better, though, the longer you stick around. Based on current mortality rates, if you're 40 and male, you're already a good bet to make it to 75, three years beyond an American's average life expectancy at birth. A man who's 65 -- an age more than 70% of the population now reaches -- can expect to live until 80. Women can expect to make 85. The real way to beat the house is by extending your health span, not just your life span. Personal example: My paternal grandfather quit professional life at 60 to go home to Mississippi and farm. He worked hard and happily every day of the rest of his life and died at 82 of a heart attack while picking his beloved blueberries. My maternal grandmother, on the other hand, lives on at 92 in a north Alabama nursing home. For the past six years she's been unable to recall -- within seconds after we depart -- whether anyone has visited her. Grandpa won, hands down. But isn't our fate simply in our genes? No. It's true that a strong genetic predisposition to, say, lung cancer can bring you down no matter how virtuous your habits, just as the reverse may permit you to puff three stogies a day until age 100. But much recent research, notably a study of Danish identical twins by American demographer James Vaupel, suggests that genetic factors account for no more than 30% of variance in life spans. What you do matters. So what's the program? Rule No. 1: Don't smoke, or if you do, quit. A 40- year-old male with a pack-a-day cigarette habit can expect to die seven years before his nonsmoking peer. Anyone who still thinks this issue is debatable is smoking something, all right -- but it's not tobacco. Next, fasten that seat belt. Doing this regularly extends life expectancy by 69 days. That may not sound like a lot, but it's one of the most significant remaining ways to improve your odds on longevity. By comparison, a healthy man at 40 who lowers his cholesterol count from 280 to 240 adds, on average, just seven days to his life. So if the prospect of too much virtue makes you sick, stick with the steak and hold the smokes. And while you're at it, have a glass of wine. Heck, have two! Heavy boozing is definitely not recommended, but various studies conclude that people who have one to two drinks daily live longer than those who never drink at all. If you're over 40, you should also consider consuming a little extra vitamin E. Physicians have been reluctant to endorse nutrient supplements, fearing that Americans would assume they could pop a few pills and then keep pigging out on Cheetos and French fries. It is important to eat right. Your best guide is the bushman's diet now promoted by the U.S. government: loads of fruit (four servings daily) and vegetables (five), plus lots of whole grains and some lean meat. Even that, though, won't deliver the high levels of vitamin E that have been linked in epidemiological studies to lower risk of heart disease, and shown by scientists with the Department of Agriculture's research center on aging and nutrition at Tufts University to improve functioning of the immune system in older men and women. How much E is enough? Official guidelines are still a few years away. But many experts interviewed by FORTUNE have, in the past year or so, begun taking a daily pill containing 400 international units -- more than 12 times what's in the typical multivitamin. Some also take 15 to 25 milligrams of beta- carotene and 1,000 milligrams of vitamin C -- though the consensus on their efficacy is less strong. Finally, there's exercise. Yes, you need it, and, no, you don't have to train for a triathlon to reap large benefits. Half an hour of vigorous walking three times a week -- shoot to cover a mile in under 15 minutes -- can cut the risk of heart attack, stroke, diabetes, and even cancer by 55%. You might also | consider a little twice-weekly weight-lifting. Aerobics has many virtues, but it doesn't fight the fall in bone density and rise in muscle weakness that accompany aging. Most important, and contrary to received medical opinion until fairly recently, the case for working out strengthens as we grow older. One Stanford University study tracked the health of some 500 runners ages 50 and over against a comparable group of nonrunners. When the eight-year study began, the runners had a 2-to-1 advantage over the others in various measures of health. At the end, their edge had increased to five times. The gap was widest among 75- to 79-year-olds. As Bob Butler of Mount Sinai Medical School says, ''Two of the worst pieces of advice an older person can receive, we've learned, are: What do you expect at your age? and Take it easy.'' That goes for mental exercise as well. Consultant Joseph Juran is one of the godfathers of the postwar quality movement and, at 89, a man with considerable standing on this subject as well. Says he: ''My personal theory is that the key to aging successfully comes down to keeping your mind active.'' Indeed, the biochemistry of the brain, neurologists agree, supports the notion that it may well function better -- and longer -- when we keep those nerve cells firing. Have we mentioned happiness? That's definitely one of the essentials too, as are friends, offspring, a spouse, and other reasons to live. Smile, hug your kids, be silly sometimes, and smell those darn roses whenever possible. If all this leaves you thinking that a remarkable amount of the latest aging research seems aimed at elaborately and objectively verifying what most of us already thought we knew, well, you're right. ''Our grandmother always said, 'People don't wear out, they rust out,' '' recalls Don Feigenbaum, 67, who along with older brother Val, 73, runs a thriving systems engineering company that numbers Tenneco and Ford among its clients. Grandma Feigenbaum gets the last word: Use it or lose it. -- R.I.K.

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