Choose 4 of the 6 following plank intensifications, and hold each one for 1 minute with a 20 second rest in between.  But first, if you need a refresher on how to do a perfect standard plank: Place your forearms on the ground, shoulder-width apart, parallel to one another. Create a fist with your hands, dig your toes into the ground to get a grip, and then lift your butt to where your shoulders line up with your hips and ankles.  Hardstyle Plank Assume standard plank, then tighten abs, as if bracing for a punch to the belly. Squeeze butt to make it visibly firm. Create static tension throughout body by imagining you’re stuck in dried concrete, mentally pulling elbows towards toes and toes towards elbows (without actually moving these parts). You will feel your thighs, triceps, and back muscles tighten up. Hold 1 minute. MORE: 4 Moves To Slim Your Hips And Thighs Decline Plank Assume standard plank. Step feet onto slight incline, like an ottoman or step. Feet should be just slightly higher than shoulders when you’re new to this move. As you get more comfortable with decline planks, select a prop slightly higher, like a plyo box or a chair. Hold 1 minute. Weighted Plank Add weight to your body—which will make your abs work harder—by using a weighted vest. This one adds 10 pounds to your body weight, and is super slim and compact. Don’t have a vest? Load up a backpack with 10 pounds of stuff (try bags of flour or rice from your pantry). Assume standard plank position and hold 1 minute. 3-Point Plank A great way to intensify any stabilizing exercise is to remove one balance point. Assume standard plank, lift 1 foot off ground, and place it on opposite inner thigh—the move will resemble a horizontal yoga tree pose. Try to keep body completely level without shifting to stable side. Hold 30 seconds on right side and 30 seconds on left side.  MORE: 9 Proven Ways To Lose Stubborn Belly Fat Arched Side Plank Assume standard plank. Rotate hips to side and lift top arm overhead.  Hoist hips higher to form convex shape (like outside of bowl), and allow top arm to angle toward floor. Hold 30 seconds on right side and 30 seconds on left side. Reverse Plank Sit on floor with legs straight out in front. Place hands behind back with palms facing in toward body. Grip floor with palms and heels, then lift butt up. Squeeze butt tightly and point toes. Shoulders should line up over hip bones, which should line up over ankles. Hold 1 minute.