A friend is visiting from out of town and suggests the two of you go hiking. You haven't hiked in years, but it sounds like fun, so you go for a five-miler along the trails of a local forest preserve. The next morning, you wake up—and you can't move. Wow, that hike didn't seem that tough, but it must have been a better workout than you thought! We hate to break it to you, but no: pain does not equal gain, and soreness does not mean you got a good workout. The good news? The reverse is also true.