Lie face up, with your back flat on an exercise mat and legs extended directly overhead, at 90 degrees to the floor. Extend your arms out to the sides, level with your shoulders in a T-position. This is your start position. Maintaining straight legs, move your legs to the left towards the floor. Do this slowly and with control thoroughout. Be sure to keep your core braced and not let your lower back arch as you lower your legs to the floor. Pause at the bottom of the movement, with your legs hovering off the floor. Reverse the movement and perform the same movement on the opposite side. Perform this alternating movement for the required number of reps (or time).