You need to learn a few things and plan your activities according to some goal. For instance if you want to build a muscle, you exercise it to exhaustion and then let it rest for about two weeks while you work on something else. While you are resting you can study anatomy so you know the major muscles, where they are, and how to exercise them. You need to study some books about nutrition so you know how to eat right, instead of just buying every fad drink that is advertised. It's smart to work out, but part-smart is not good enough.