You could be motivated to workout for health reasons but you must have the willpower to do so. With these two combined at high limits it can push you to success and greatness. First you have to find out what motivates you. More importantly, where does willpower come from? Are you born with traits that promote emotional override(willpower).
Everyone can be motivated but not everyone is motivated the same way. Perhaps willpower comes from past experiences and learning to push yourself or it is doing something to accomplish something greater than yourself.