Don't talk on your cell phone while you stroll on the treadmill, and especially don't have 45 minute conversations and most especially don't do it while I'm running!

Don't incline the treadmill to the max and then walk hanging on to the control panel for dear life. It doesn't do anything for you and it's bad for the treadmill causing it to break down more often, meaning I can't use it while it's out of order.