When you will find your reason to do it, you will feel that fire within you. The kind of motivation that makes you keep going while others give up! This is not just advice for the gym, it is advice for everything in your life.
Isnt driving a point home one of the trickiest things to do when you talk to your children? Clichéd words and principles will never make them understand what you try to tell them or what you expect of them.