Frog Sit-Ups

Lie with your back flat on the floor (or exercise mat) and your legs extended in front of you. Now bend at the knees and place your outer thighs by the floor (or mat) as you make the soles of your feet touch each other. Now try pushing both soles and bringing them up as near you as possible while you keep the outer thighs on the floor (or at least almost touching it).