SETUP: Lay flat on the floor. Keeping your legs close together, raising them slightly off the ground and pushing your lower back down into the floor. This will “switch on” your abdominal muscles.
REP: Keep your legs straight and start moving them over & under, across the mid-line of your torso. Focus on maintaining the tension in your abs. Big breaths out.
TIP: Look at your feet as you work. This will mean lifting your head slightly, and doing so will push your lower back flat, preventing you from rounding your back.