Any workout routine can get boring. What's more, if you're already pressed for time, it's easy to skip the most monotonous activity on your schedule. But that's one of the beauties of a high rep workout. You can get creative and simultaneously save time by designing your own circuit training plan.
Select six exercises and complete one high-rep set of each with very little rest in between. For example, you could do 30 push-ups, followed by 50 sit-ups, leading into 25 squat thrusts. Finish with 30 calf raises (both calves done simultaneously), 20 curls per arm and 25 tricep extensions per arm. You'll get a challenging workout that won't even give you a chance to be bored. In addition, it'll only take about 15 minutes out of your day [source: Marinello].