One key aspect of exercise is balance. Why? Because like all other physical abilities, it diminishes with age unless we consciously exercise it. Is that a bad thing? Only if you fall down and break your hip or wrist. Here's a simple balance exercise you can do daily. It takes just a couple of minutes and will produce quick improvement.
If you really want to improve your balance, many yoga poses are specifically designed as balance poses, utilizing arms, legs, hips -- the entire body, in fact. On a more modern note, there's a whole new breed of vibrating-platform exercise-equipment that makes use of forcing you to balance while working out. The net effect is that because the balancing aspect forces you to use an entirely separate set of muscles in addition to your normal work out muscles, it dramatically accelerates the benefits of exercise.