Lie on a stable surface.
Make sure your legs are bent, not flat.
Now, this is where everyone goes wrong. Most people say, put your hands behind your head with your elbows in line with your hands. Actually, you have to put your elbows in front of your hands.
Once you are lying down on the floor like that, lift your upper body up, and set it down. Repeat. You now know how to do a proper sit-up! Please comment and follow me!