Your body is the one possession that you know you will have for the duration of your life. It's your vehicle, entertainment center and dwelling all in one. So for the same reason you would take care of your computer or clean your house, you should take care of your body. Exercise is one of the best things you can do for both your body and your mind.
Indeed, thats my motivating power too! It is really hard to continue and be consistent especially when there are a lot of distractions.