with willpower.

because in life I have been in a lot of situations that I could not control, and situations with my body in particular where I could not control it... sometimes it was my own choice to turn to drugs that made me have no control over my body, and other times it was under the control of bad-hearted people... but regardless, working out lets me control how my body feels when I wake up, and what I see when I look in the mirror. When I am too tired to run an extra mile I say to myself "you are in control of your body, and if you want to do something bad enough, you can make your body do it" ... and so it goes.