Watching TV, listening to music, and perusing magazines are all great ways to pass the time when you're on a cardio machine, but even those can get boring. They also require a bit of attention, compromising a good workout — you can't turn pages while doing sprint intervals. When you need a little motivation, utilize your fellow gym-goers and compete with a stranger. While on the treadmill, look for someone near you who is clearly working it, and try to run a little faster or stay on the machine a little longer than that unsuspecting runner. When they end their run and you're still going, get ready for the sweet taste of victory. This works on a bike, elliptical, or in the pool. While it's helpful to use someone else's drive to push yourself, just make sure you also listen to your body and don't exceed your personal limits.