If you don't think planks are hard enough, try this move

Your abs will hurt every time you laugh tomorrow.

Check out Women's Health's FitGIF Friday every week for fun and challenging new moves to make your sweat sesh really count. Here's this week's exercise:

Plank knee taps: Amp up your abs workout with this simple plank variation. Like the classic plank, this will strengthen your core and upper back, but by adding the taps, you're making it 1,000 times harder.