Doctors that diet and exercise are the best ways to stay healthy, but few people get enough exercise. Only a fifth of Americans get the recommended 150 minutes of strength and cardiovascular activity per week and more than 80 million Americans over age 6 are entirely inactive. It doesn’t help that many U.S. school gym classes. Nearly half of high school students don’t have a weekly PE class while only elementary school require PE at least three days a week. People leading an inactive life pay a price. They are at serious health problems, including heart disease and cancer.