skinny-bitches-only: Do this workout to

skinny-bitches-only: Do this workout to tone up and get that flat stomach! explanations: jack-knife sit-ups butterfly crunch plank raises: get in a plank position, then without moving your arms or legs, bend your hips so that you are in a downward dog position (but still on your elbows). Then return to your starting original plank position. That’s one rep.