The logic seems so simple. Compared with the rest of the world, Americans are fat and getting fatter. We know perfectly well that being overweight causes health problems. We also know that regular exercise will help us lose weight. Therefore, if we want to live longer, healthier lives, we should exercise more.

"If only it were that simple," you say? Well guess what? The exercise part is that simple. The hard part is convincing ourselves to be proactive about fitness.

The statistics in favor of exercising are undeniable, but as a nation we seem to have become immune to such numbers. When experts tell us that 58 million adult Americans -- about a third of the population -- are overweight, do we stop and look at our own lifestyles? When we hear that weight-related conditions are the second leading cause of death in the United States (behind smoking), do we think, "Better go for a brisk walk," or do we plop down on the sofa, thinking, "Well, at least I don't smoke." When we're told that a mere 20 minutes of physical activity a day can reduce our stress levels, are we motivated enough to pump up our tires and go for a bike ride with our kids?

One of the collective hurdles Americans need to jump, suggests ShapeUp America, an organization founded by C. Everett Koop, is the importance we give to the reflection in the mirror. America's weight problem is too often defined as an appearance issue rather than a health issue. Similarly, exercise is often perceived as punishment to living large instead of a fun way of living well.

Why do we find it so difficult to maintain a healthy level of fitness? "Our environment has changed," says Sheridan Robinson, a licensed counselor in health risk management. "Years ago, when we did things without computers, we were forced to be more active. Now there is a need to plan activity. It used to happen naturally."

Finding a way to fit exercise into your everyday life is one of the surest ways to improve your overall health. It's not a piece of cake, but once your body starts expecting that activity every day, it's a lot easier to keep it up.

In this three-part series we will try to convince you why you should bother with an exercise regimen, how to get started with an activity you enjoy, and most important, how to maintain the healthy lifestyle you create.

Why Bother?

Nine reasons to get moving

Keep the blood flowing. Exercise is powerful ammunition in fighting heart disease. Regular exercise lowers blood pressure and resting heart rates, raises "good" (HDL) cholesterol levels, and helps to maintain a healthy weight. Three 30-minute sessions of exercise per week improves cardiac health, but to see weight loss results, you probably need to bump it up to five.

Meet your great-grandchildren. A 25-year study of Harvard alumni found that, in general, the more a person exercises, the better his chances are to outlive his peers. In the study, Dr. Ralph S. Paffenbarger found that men who walked nine or more miles a week had a 21 percent lower mortality rate than those who walked three or less miles a week.

Stand up straight. Exercise increases bone density, which is especially important for people at risk for osteoporosis. A weight-bearing exercise, such as walking, dancing, or moderate weight-training, can help maintain or increase bone mass.

Buy extra large baby clothes. Researchers at Columbia University found that women who burned between 1,000 to 2,000 calories a week through moderate exercise gave birth to infants weighing 5 to 10 percent more than babies of inactive moms. Larger babies tend to be stronger and better able to handle physical adversity.

Save money on Prozac. Aerobic exercise often improves self-esteem, reduces anxiety, and relieves depression. Research shows that stress levels tend to be lower in fit people than in sedentary people and that regular exercisers cope better with anxiety.

Notice the little differences. "I'm a better mom," says Sheridan Robinson. "I find that when I'm not physically active, I come home from a day at work more tired and irritable. I'm not as patient with my son as when I take the time to do just a half hour of walking." And she doesn't toss and turn at night. "I have a tendency toward insomnia . . . but when I'm exercising regularly, I sleep all night."

Bite bugs back. Moderate exercise has been shown to strengthen the immune system. The key is finding a training balance and eliminating other immunity attackers, such as malnutrition, stress, and quick weight loss.

Fight disease. Because fit women produce a less potent form of estrogen than sedentary women, they can cut by half their risks of developing breast and uterine cancer and decrease by two-thirds their risk of contracting the type of diabetes that most commonly affects women.

Sharpen your mind. Regular aerobic exercise appears to help preserve neurological functioning as people age and may enhance it as well in older people who have been sedentary.

Acknowledging that exercise should be a part of your life is the first step toward better fitness. Getting off the sofa is next, and we'll walk you through it in the next article of this three-part series, "Off the Couch and Out the Door."

Further reading

To learn more about the benefits of exercise, see the Rx.com Guide to Lifelong Health .