A workout’s benefits derive from exercise itself, not how much you sweat. The more intense the effort, the greater the health benefits and, generally, the more you sweat (your body’s natural response to your core temperature rising). But perspiring, in and of itself, does not amplify those effects (not even calorie burning). You could sweat a lot due to a hot or humid environment, and you wouldn’t get any extra fitness benefit.—Gretchen Reynolds, from The New York Times