If you're cranking out the crunches and seeing minimal results, it's time to rethink the way you work your core [1]. Enter this quickie routine from Megan Roup [2], creator of The Sculpt Society. Using a pair of sliders [3] or two hand towels, you'll complete this entire circuit in a plank position, working all those hard-to-hit abdominal muscles [4] that will sculpt and strengthen your core. Start by doing all of the moves on the right side before going on to the left, making sure you perfect your plank [5] before you place the sliders or towels under your feet. Do the entire circuit twice on each side for a fast burn you can squeeze in anywhere.

Knee Pull and Cross Body

• Start in a plank position with sliders or towels under your feet.
• Bend and slide your right knee into your chest and hold for one to two seconds; slide the leg across your body, as shown.
• Do eight to 12 reps before switching legs.

French Twist

• Start in a plank position with sliders or towels under your feet.
• Cross your right foot over your left foot and rotate your hips to slightly face the left side.
• Actively engage your obliques as you curl your spine and bend your knees into your chest.
• Do eight to 12 reps before switching sides, crossing your left foot over your right and rotating hips to face the right side.

Side Plank With Knee Pull

• Start in a side plank [6] on your left side (no slider or towel needed) with your left elbow resting directly under your shoulder and your hips stacked. To make the move more challenging, you can place a Pilates ball under your right hand.
• Pull your right knee into your chest and hold for one to two seconds before tapping your leg back in the starting position. Keep your body lifted at all times by engaging your obliques.
• Do eight to 12 reps before switching sides.

Thread the Needle

• Start in a side plank on your right elbow (no slider or towel needed).
• Thread your left arm through the open space beneath your waist, as you rotate your shoulders and hips slightly toward the floor.
• Make sure to move from your shoulder, squeezing the side oblique muscles with each rep while maintaining proper form in your plank.
• Do eight to 12 reps before switching sides.