Vary Your Routine
Boredom and monotony can settled in quickly if you do the same thing every time you work out. Do a different cardiovascular exercise each time. For example, hit the treadmill one day and ride the stationary bicycle the next. Also, vary your weight-lifting schedule. Isolate a different part of your body for each workout and work those muscles hard. Hit your arms and shoulders one day, your back the next, etc.