Adding sit-ups to Push-ups

Sit-ups. 

Oh I'm gonna hate these! These are my instructions. Note: Moving my head like this may make me dizzy.

Start by lying on your back with your knees bent and feet placed flat on the floor. Wedge your toes underneath a couch or bed frame to keep your feet planted. With your hands behind your head (don't pull yourself up by the neck), begin your sit-up. Instead of going all the way up to your knees, stop halfway and pause before returning to the ground. Doing so alleviates tension in the lower back, while isolating the middle and upper abdominals.