If you’re looking for motivation to be more physically active, you may find it in a recent study that shows, in addition to its other health benefits, exercise may reduce the risk of 13 types of cancer. In the study, conducted by researchers at the National Institutes of Health and the American Cancer Society and published in the May 2016 edition of the JAMA Internal Medicine, researchers examined the physical activity levels of  1.4 million people over an 11-year period.