my fiance has a car that she commutes with, but i do not. so if i want to get to the work in the morning, i have 4 options - bike, train, cab, or walk. walking takes too long (4+ hours one way), cabs are too expensive ($30+ one-way), and the train isn't terribly fun and still costs money ($4 one-way), so the bike usually wins!

bike commuting isn't a state of mind for me, it's merely my best option most of the time.