My circuit is a high-intensity rush. You can finish the workout in about 40 minutes. In a few spots throughout the session, you can choose to rest completely or perform "active rest" exercises like jumping jacks, push-ups, burpees, or mountain climbers. Whether you rest or stay active, you will get the best possible workout you can do in this window.
When I was in the military, I didn't have a lot of time to work out during my long days on duty. To combat the time crunch, I made a full-body circuit workout to take advantage of every second in my workout. If you like to train fast and hard, this workout is for you.
This workout includes two exercises per large muscle group—legs and back—and one exercise per small muscle group. Most people don't like doing legs, so I put them first in this session. Exhaust your legs right from the start to fire up your metabolic furnace and make your entire workout harder.
Right after you work on your legs, you've got a superset for back, and then you'll finish with a series of exercises for the smaller muscle groups. At that point, there is no rest between exercises or supersets!