The mind and the body are interrelated: what you do to one necessarily effects the other. There must be a balance between the two. If your body is strong but your mind is weak, you are a powerful instrument with no direction; such an instrument rarely produces good. If your mind is strong but your body is weak, then you may be filled with purpose and good intentions but have no strength necessary to act on your impulses. You must strengthen your mind to control your body; and strengthen your body so you can always follow the good directions of your mind.