A new study in the Journal of Strength and Conditioning Research shows that the length of workouts doesn’t matter. The Danish researchers compared nine shorter sessions to three longer ones, and found absolutely no difference in results.

What does make a difference? How hard you work.

Related: THE 21-DAY METASHRED—an At-Home Body-Shredding Program From Men’s Health That Strips Away Fat and Reveals Hard Muscle

If you’re willing to push yourself for 20 minutes, this new calorie-crushing metabolic complex from Men’s Health Fitness Director B.J. Gaddour will improve your aerobic power and muscular endurance while giving your glutes, thighs, shoulders, and triceps a solid training stimulus.

preview for 20-Minute Kettlebell Metcon

All you need is a single kettlebell, which you’ll use for 15 swings, 10 goblet squats, and 5 shoulder presses with each arm. Rest as much as you need, and repeat as often as you can for 20 minutes.

The first few times you do the workout, try to increase the number of rounds you do in those 20 minutes. Then increase the weight and repeat the process.

Related: 6 Brutally Tough Workouts You Can Do on Your Lunch Break

The reward is a body that’s leaner, faster, more athletic, and better conditioned for any challenge that comes your way.