Continue, another 2 minutes like this ...
Help yourself with your legs, sit up like I am, squeeze hard with your hands.
1 minute still, wring out loud.
now take the two hard-faced books / dvd cases, put one between the left leg and the left ball and one between the right leg and the right ball, now close the legs, try to make the knees touch each other, tighten as much as possible and as strong as you can. 2 minutes.