Lie on your back with bent knees and your feet flat on the ground. Bring your arms overhead against your ears. If you want to get fancy with your sit-up, cross your arms at the top so your palms press together.
Press your lower back into the ground and engage your core while you tuck your chin into your chest and curl upward.
Come into a full sit-up, keeping as much of your feet on the ground as you can and your arms by your ears.