I think this quote is probably more applicable to running than most of my previous ones:
"Pleasure is a by-product of doing something that is worth doing. Therefore, do not seek pleasure as such. Pleasure comes of seeking something else, and comes by the way." - A. Lawrence Lowell
"Habit is necessary; it is the habit of having habits, of turning a trail into a rut, that must be incessantly fought against if one is to remain alive." - Edith Wharton
