Rocking Chair Abs
To do Rocking Chair Abs, start half-kneeling with your back knee slightly turned out and your hips extended and glutes squeezed. Your chest should be up nice and tall.
Then sit your butt back and round your back as you tuck and roll onto your back. As your roll back, switch the leg crossed underneath so that when you roll back up you can come to a half-kneeling position on the other side.
Use your arms for momentum only if needed. Less arm swing makes the move tougher. Less momentum in the roll makes the move harder.
Do not touch your hands down to help you come back up to half-kneeling. Keep alternating sides, squeezing your glutes at the top. Press your chest out and half-kneel nice and tall at the top.