I've heard a lot of excuses for not exercising, but the most common is “I don’t have time.” I would argue, however, that most everyone has at least 15 minutes a day—and that's all it takes to complete the workout below, or one of the workouts I'll share with you over the next couple of months.
If you complete each of the workouts during the week, you'll have worked all of your major muscles, equaling a complete body workout. For each of the workouts, perform the exercises back to back.
After finishing exercise 4, start over with exercise 1 and repeat the whole routine 2–3 times. If you can complete each set with zero to minimal rest, you will be able to complete 3 sets of 20 repetitions in 15 minutes. If you are just starting out, try for 2 sets of 10 repetitions.