 So here's how to stay safe. Start by making sure there's a safe amount of distance behind the treadmill in case you fall off. Wear clothes that fit, shoes that are tied. Whatever you do, do not skip clipping that safety key to your shirt. Very important. As one expert put it, it'd be kind of like driving without a seatbelt. 99% of the time, you're not going to have to use it, but when you need it, you really need it. And wherever your treadmill is moving, kids and pets, they should be in a different room.