Plyometric exercises are challenging and ideal if you're short on time. You can design an effective 15- to 20-minute, high-intensity workout with a combination of such exercises as jumping jacks, squat jumps, lunge jumps, squat-thrust jumps, mountain climbers and high knees. For a boot camp-style training session, perform each exercise for one minute with a 30-second recovery between exercises. Rest for three minutes after completing the first set, and then complete two more sets.