Towel Workout Breakdown Use 30-second intervals of work followed by 10 seconds of rest. You’ll go through this sequence 9 times, for a total of 45 rounds. This workout takes 30 minutes, but if you want to cut it back to 20, just go through the whole sequence 6 times instead. Complete as many reps of the exercise as you can (without sacrificing proper form) during the 30 seconds of work.
Five-Minute Ab Workout