Start lying face up on the floor with your legs outstretched.
Engage your abs to lift your feet and shoulders just off the floor, then kick your right leg toward your face, holding onto your shin or ankle with both hands.
Without dropping your shoulders or allowing your feet to touch the ground, switch legs, lowering your right leg and pulling your left leg toward your face. Try to inhale while you're switching and exhale while you're pulling the leg toward your face.
Do 10 to 15 reps. Every time you switch legs, it counts as one rep.