Surgery.
I had surgery on my foot. 4 bones fused together, and the doc told me that if I would stop smoking, change my diet, get into shape i would heal much faster and stronger. Since I was looking at a nine month recovery I thought anything I could do to shorten it would be beneficial to my sanity. The thought of lying back on the couch, with my foot up in the air for nine months watching daytime television was enough to motivate me to go to the gym - been there ever since!!