If there were a drug that treated and prevented the chronic diseases that afflict Americans and we didn’t give it to everyone, we’d be withholding a magic pill. If this drug was free, in a country that spends more than $350 billion annually on prescription drugs, where the average 80-year-old takes eight medications, we’d be foolish not to encourage this cheaper and safer alternative as first-line treatment. If every doctor in every country around the world didn’t prescribe this drug for every patient, it might almost be considered medical malpractice.

We have that drug today, and it’s safe, free, and readily available.

Exercise has benefits for every body system; it is effective both as a treatment and for prevention of disease. It can improve memory and concentration, lessen sleep disorders, aid heart disease by lowering cholesterol and reducing blood pressure, help sexual problems such as erectile dysfunction, and raise low libido. Exercise does it all. Even with cancer, particularly colon and recurrent breast cancer, the data show clearly that exercise is a deterrent. Newer studies on a glycoprotein called Interleukin 6 suggests that general body inflammation, a factor in almost every chronic disease, is reduced by regular exercise.

The United States currently spends more than $2.7 trillion, roughly 17 percent of GDP, on a health care system that is financially incentivized to treat disease. The more tests that are run on patients, the more medicines that are dispensed, the more procedures that are performed, the greater the financial burden for us all. Despite far outspending any country in health care, the United States is currently ranked 28th in life expectancy. Our current system does very little to encourage preventive health care. We are mortgaging our country’s financial future to pay for increasingly expensive treatments for the same diseases we could effectively delay or prevent.

Professionally and personally, I have made dispensing the drug of exercise a large part of my life. I treat limping and hobbled athletes of all ages in my sports medicine practice at the Hospital for Special Surgery in New York City. My waiting room is filled with 8-year-old gymnasts to 80-year-old marathoners, all wanting one thing: movement. My job is to fix their aches and pains and to keep them going. Before and after work, I am one of them, an avid athlete who has run 30 marathons and 11 Ironman triathlons. I’m what you might call an exercise fanatic.

There probably is such a thing as too much exercise, but I’m much more worried about inactivity. As my colleague Bob Sallis, past president of the American College of Sports Medicine, says, “Lack of fitness is the public health epidemic of our time.”

Seventy percent of Americans are overweight, 30 percent are obese, and only a very small fraction exercise for the 150 minutes per week recommended by the American Heart Association. What can we do to motivate them?

In a recent study, Kevin Volpp from the Center for Health Incentives and Behavioral Economics at the University of Pennsylvania took 56 morbidly obese, middle-aged, male participants and studied systems to incentivize weight loss. In the world of obesity, morbidly obese men are tough customers; it’s very difficult to get them to change their behavior patterns. Obesity and related conditions and diseases, including high blood pressure, diabetes, and high cholesterol, account for more than 50 percent of annual health costs in the United States. Solving the obesity epidemic is the key to reducing health care costs.

Volpp randomly divided subjects into three groups: a control group and two financially incentivized groups, in a study in which the goal was to achieve a 16-pound weight loss over 16 weeks. The control group was weighed at regular weekly intervals with no financial reward. One financially incentivized group was given a fixed sum of money weekly that they could win if they hit their target weight-loss goal per week, and the other group was enrolled in a lottery system in which they had the chance of winning smaller or larger amounts of money but could qualify for payment only if they hit their weekly weight goals. Subjects from all three groups were educated on the role of exercise and nutrition for weight loss at the beginning of the study. After 16 weeks, both the fixed payment and lottery system subjects had lost more than 16 pounds while the control group had not. The financial incentive was relatively small, averaging $350 in total payments over 16 weeks. This isn’t a long-term solution: Four months after the study’s completion, most subjects had returned to their prestudy weight. But it shows that even the most challenging cases of obesity can be helped with the right incentives.

In the United States, we routinely incentivize behaviors deemed conducive to a highly functioning society. Financial incentives encourage marriage, having children, owning property, even accruing debt. As much as we believe we are free to choose, Big Brother’s tax code is pulling our strings from above. I’m not arguing that this is poor policy. On the contrary, encouraging favorable behavior for the greater good helps keep the fabric of our society together and the wheels of our economy turning.

When I began writing The Exercise Cure, my thought was to provide a guidebook to encourage healthy behavior. Having investigated the correlation between disease and fitness, I now believe that we can save billions of health care dollars by incentivizing movement. Rather than mortgage our financial future on a bloated health care system that isn’t doing a very good job of making us healthy, we’d be much better served by incentivizing people to get off the couch. Ideas to make this happen include lowering health care premiums based on activity levels: The more steps you take per month or year, the less you pay. This doesn’t have to be large amounts of money—even a little bit of incentive goes a long way. We also should encourage the use of a fitness vital sign for annual medical checkups where the amount of physical activity that someone is doing per week is monitored in the same way heart rate and blood pressure are. These methods will help encourage movement and health and will reduce disease prevalence.

I can’t promise you that if you work out daily you won’t get sick. I’m also not suggesting that exercise cures all ills. Genetics, chance, socio-economic, and other factors clearly play significant roles in affecting health profiles. What is becoming increasingly apparent, however, is that the drug called exercise can help prevent, alleviate, or treat almost every disease state. I hope my book inspires you to take it for yourself.