This is a Pilates exercise and is excellent for trimming the waist and toning the tummy. Lie on your back on a yoga mat. Bring the hands behind the back of the neck, lift and twist the upper body to one side and bring your elbow towards the opposite knee. Inhale, lower back down. Exhale, lift and twist towards the other side, inhale return to starting position. Keep this movement going and you can start to speed it up a little bit once you get comfortable with the exercise. Then, start to extend one leg out as you go. Keep pulling the lower tummy muscles up and breathe deeply. To advance it further, you can start to tap the heel of the extended leg on to the floor. This will work the lower tummy muscles even more therefore giving support and strength to the lower back. Aim for doing it for 30 seconds in one go.