Even if you're a cardio fanatic, running on a treadmill can become a bit stale. To fight boredom you need to mix up your program with intervals and adding incline work. I just made a downloadable version of four of my favorite treadmill workouts, so now you don't have to go to the gym empty handed and come up with cardio routines on the fly. You can print out this PDF of treadmill workouts and take it to the gym. After printing, just fold the paper into fourths so you can easily follow the workout you've selected.