I'm interested in knowing what motivates other riders. My breakdown is about like this:

Health/Exercise/Weight control : 80%
Mental health (sanity) : 10%
Competition (to crush souls) : 0%
To see how strong I can get : 10%
To get away from the spouse/kids/etc. : 0%
It's just fun! : 0%
Transportation : 0%
Other : 0%

** Note to Ryanf: The breakdown should total 100%