Sit with your back straight, knees bent towards your chest. From here, lean back slightly, engaging your core. Bring your legs together and lift your feet off the floor. Your hands should be together in front of your stomach, sticking your elbows out to the side. Now, twist with control from one side to the other, aiming to touch your elbow to the ground with each rotation. Move continuously through this sequence, maintaining a firm back and core. Get the most out of this core exercise by holding your back straight and twisting from your upper body; your legs should remain stable.