Lie flat on your back with your arms held out in front of you pointing to the ceiling. Then bring your legs up so your knees are bent at 90-degree angles. This is your starting position, and it’s vital to get your back as flat against the floor as possible. You shouldn’t be able to get a hand in between your back and the floor, and you need to maintain this position.
Slowly lower your right arm and left leg at the same time, exhaling as you go. Keep going until your arm and leg are just above the floor, being careful not to raise your back off the ground. Then slowly return to the starting position and repeat with the opposite limbs.