Exercise is one of the few activities in life that is indisputably good for us—an undertaking that extends enormous benefits but extracts few costs. Exercise helps us live longer. It fends off heart disease and diabetes. It reduces our weight and improves our strength. And its psychological value is enormous. For people suffering from depression, it can be just as effective as medication. For healthy people, it’s an instant and long-lasting mood booster.15 Anyone who examines the science on exercise reaches the same conclusion: People would be silly not to do it.
