Russian Twist

Sit down with your knees bent. Grab your knees and lean back until your arms are straight. Release your hands from your knees. Your abs should be engaged to hold you in this position. You should be sitting back about 45 degrees. Clasp your hands together and rotate them from side to side. Aim to touch the ground on the opposite side of your body. Optional: To make it more difficult, you can lift your feet off the ground

If you feel pain in your lower back, come up higher. Make sure to pull your belly button towards your spin to engage your your abs even deeper.