1. You can strengthen your core without moving a muscle. Whereas most muscles propel you, your core resists movement—for instance, to protect your spine when you twist your torso. So don’t be surprised by how hard it is to stay still in this core workout. You’re conditioning your core to do its job more effectively.

2. Slouching sabotages your six-pack. Training your core helps correct poor posture. But an hour a week of core work can’t compensate for the 50 hours spent slumped over your keyboard. The fix: Stay tall through your hips and keep your head up and shoulder blades back and down all day long.

3. Core muscles contract first in every exercise.All the energy you exert originates in your torso, before being transferred to your arms and legs. So a weak core reduces the amount of force you’re able to apply to a barbell. When you hit a plateau in presses, squats, or any other strength move, ask yourself if you’re training your core as hard as you can. (Do you want to build the ripped, chiseled abs you always wished you could have? It only takes 82 days with the new follow-along DVD program from Men’s Health, Speed Shred! If you like P90X or Insanity, you’ll love the metabolic workouts in Speed Shred!)