Reasons I got back into cycling:
Combat that thing called the 'Programmer's Spread' Gained 20lbs in my first year of a desk job after quitting retail that kept me on my feet 8 hours a day.
Get back in shape after jaw surgery (5 weeks on liquid diet is one hell of a diet, unless you have nothing but muscle to loose, down 22lbs in those 5 weeks) and my own little bout with cancer 5 years ago. (Malignat Melanoma Clark's level IV on my right forearm, was ~6mo from following in Lance's foot steps and I don't mean to the tour)
And most importantly: being healthy and looking good for my wedding next May to my darling fiancee Margaret.