Boat Press

Add another level to the yoga Boat position.  This will engage your upper body a bit more...

While sitting, put a weight in both hands.  Lift your legs while trying to straighten them and lift them high.  Then add the press by moving the weight up and back down to your chest.  Go as fast as you can while you keep your legs up high!

Modification - bend your legs, or even putting one heal on the floor will help with this one.  Just rotate that one heal down once in awhile to be even on both sides.