A quick note about exercising while using headphones. Studies suggest that blood flow to other parts of the body while exercising results in less blood flow to the eardrums muscles Therefore people turn up the volume louder than they should and can damage their ears. I have found this to be true as one day while mtn biking i had a couple who was walking say something to me so i stopped and ask what. They said something and i couldn't hear them even though i was only 15 yards away from them. I had to ask them a couple times. Eventually the guy picked up a rock and pointed at it and said louder "Rock on brotha"
when reading about this the author suggests marking your volume control somehow during a normal listening session and to not turn the volume up anymore than that once you start your exercise
In the beginning, I listened to music while excesses, and I eventually stop doing it, because I experienced tiresome with my ears after exercises.