Some of the folks in today's video are having a bad day while most brought their misfortune on themselves by being just plain stupid. Here's a few things one should never do on a treadmill... Never place the back of your treadmill near a wall or other painful object. Never ride a bike, ball, unicyle, etc on a treadmill. Never sit down backwards on a treadmill, especially if there is an iron post behind it. Never allow your animals on a treadmill.