Lie on your back with your hands under your butt and your legs together. Tuck your tailbone and make sure your back is completely flat against the floor.
Brace your core as you lift your legs up toward the ceiling, keeping them straight and pressed together. Make sure to keep your lower back flat against the floor.
Stop when your legs form about a 90-degree angle with your body, or as close as you can get. Keep your upper body relaxed.
Slowly lower your legs until they're hovering about an inch off the floor.