How to do it:
- Start on your back, with your hands on the floor for support and legs lifted up off the floor.
- Using your core muscles to support you and protect your lower back, keep your knees over your hips as you slowly drop both knees to the right side, forming a 45-degree angle with the floor.
- Then, fire up your obliques as you drive your knees back to the starting position.
- Repeat on the other side.