As a music therapist in a past life and having studied the effect of music on time estimation for my master's thesis, I can attest to the fact that music can make time seem to go more quickly as well as have an effect on one's physiology. During my running days (pre-iPod), I would sing to myself ("Rub Your Tummy" from "Sesame Street" was a mainstay!) to maintain my pace and ensure breath control.