Your Guide to Exercising Through the Ages

These few simple fitness investments will last you a lifetime.

man running on a treadmill

The following article comes from the U.S. News ebook, How to Live to 100, which is now available for purchase.

What's the golden ticket to living well into your golden years? A lifelong exercise program, says Pamela Peeke, assistant professor of medicine at the University of Maryland School of Medicine. Specifically, a program that adapts to your physiological needs as you age. "Exercise is age-specific," says Peeke, author of Fit to Live and Body-for-LIFE for Women. "And you want to start as young as possible."

If you wait until age 65 to start exercising, you'll still benefit somewhat: Research has shown that you can, indeed, take steps to reverse the effects of inactivity later in life, and with considerable success. But why take the hard route? Fitness is like retirement savings, Peeke suggests: Wait until later to start socking away "body currency," and you'll get much less bang for your buck. You'll be trying to amass strength and endurance just as your energy and lean muscle mass have dwindled.

But start with a simple, well-rounded fitness plan now, and modest upkeep can take you spryly into your 60s, 70s, 80s and beyond. All you have to do is stay consistent. "I've seen 100-year-olds who are more active than some 20-year-olds," Peeke says. However, most people neglect their fitness regimens as they get older: Only 30 percent of people ages 45 to 64, 25 percent of 65- to 74-year-olds, and 11 percent of people 85 and older say they exercise regularly, according to a recent study by the National Institutes of Health (NIH).

[See: 7 Mind-Blowing Benefits of Exercise]

Ready to turn aging on its head, then? This guide will lead the way.

20s: Build your fitness base. Your 20s may seem like a "freebie" decade when you can skip exercise without significant weight gain. But it's really the perfect time to start building your fitness foundation. "As we get older, we lose muscle strength and our bones become less strong," Peeke says. Start a strength-training routine now and keep it up two to three times a week and you'll be able to afford losing some lean muscle mass and bone density later, "no sweat."

Your strength-training regimen should consist of lifting weights or doing exercises that use your body weight for resistance, such as pushups and lunges, for 30 minutes. Aim for a load you can comfortably perform at least eight reps with, but no more than 12, Peeke says. Intersperse strength-training sessions with cardio workouts and you'll reap additional benefits for tomorrow: Exercising one to three hours per week can reduce a woman's risk of breast cancer by 20 to 30 percent, Peeke says in her book; four or more hours can drop the risk by almost 60 percent. For both sexes, regular cardio—at least 30 minutes of activity three to five days per week—can cut your risk of colon cancer by 30 to 40 percent, research suggests.

Your 20s are also a good time to learn what Peeke calls "positive coping skills." The sooner you can deal with life's stressors healthfully—say, by meditating or going for a jog instead of plunking down on the couch with a bottle of wine—the easier it will be to stick to your exercise blueprint long-term.

30s: Diversify. If you focused on one sport or activity throughout your 20s, now is the time to round out your exercise program, says Karl Knopf, coordinator of the Adaptive Fitness Program at Foothill College in Los Altos Hills, Calif. Swimmers who "just swim," for example, can run into posture troubles down the road, such as hunching over due to chronically tight neck, chest, and shoulder muscles.

[See: Best Workout Foods: What to Eat Before a Workout]

Cross-training is a great way to prevent imbalance and overuse injuries, says Knopf, author of Kettlebells for 50+. A swimmer might add cycling and running to the lineup, which will ensure a good mix of upper and lower body workouts. It's critical that your fitness regimen also include balance and flexibility exercises to loosen tight muscles, preserve range of motion, and prevent falls—which is important now and as you age, says the National Institute on Aging. Stretching is a simple way to maintain flexibility, and exercises such as heel-to-toe walks and standing on one foot will boost your balance. Activities like yoga, tai chi, or dancing are also good options.