Start lying on your back with your knees bent and feet flat on the floor. Be sure to keep your feet underneath your knees, not in front. Raise your arms so they're in a straight line above your shoulders. Press through your heels to raise your hips up to the ceiling, tensing your abs and squeezing your butt as you do. You should be making a long diagonal line with your body, from shoulders to knees.
Hold for a few seconds, making sure your spine doesn't round or arch and your hips don't sag. Keep your abs and glute muscles engaged.
Lower your butt to the ground with control, keeping your arms in the air.