Reverse Plank Hover

This is another move that's much harder than it looks. You'll engage your abs and just about every other muscle in your body!
How to do it: Sit with your legs extended, feet flexed, hands just outside your hips with your fingertips facing your forward. Brace your abs in tight and press down through your arms to lift your hips a few inches off of the floor. Bend your knees slightly, keeping your heels on the ground. Inhale and scoop your abs in deeper towards your back, and as you exhale, fully extend your legs and try to push your hips slightly behind your shoulders. Hold for 1 count. Bend your knees and return hips under your shoulders to gently lower to the floor. That's one rep. Repeat up to 3 sets of 10 reps.
Make it harder: Instead of lowering your hips back down to the ground in between reps, try to keep them lifted off the floor the entire set.
Mind your muscle tip: Focus on lifting and moving your hips with your abs, only using your arms and legs for assistance.source by www.shape.com