You could carry your burdens lightly or with great effort. You could worry about tomorrow or not. You could imagine horrible fates or garland-filled tomorrows. None of it mattered as long as you moved, as long as you did something. Asking why was fine, but it wasn't action. Nothing brought the rewards of moving, of running. Sometimes you just do things.
Scott Jurek, Steve Friedman (2012). “Eat and Run: My Unlikely Journey to Ultramarathon Greatness”, p.94, A&C Black