My health: management of T1 diabetes.
It is fun.
I love competition with myself and others.
Bike stuff.
Hanging out with other bike nerds.
Racing.
I love the pain a hard ride brings, the kind that lingers all the following day and while working I can remember why I work at all (see the fourth reason above).
Sitting down is boring.
Eating tons of food.
and finally, I ride for a good lead-out...