Lie face up on the floor with your legs extended over your hips, toes pointed, hands behind your head. Open your legs into a straddle position, only as wide as you can go without allowing your lower-back to arch. Use your inner-thigh muscles to bring your legs together. Continue squeezing your inner thighs as you cross your lead leg over your right and lift your head and shoulders off the floor. Lower your head to the floor as you return to your straddle position. Repeat the move, alternating your lead leg.