Grab a pull up bar with a pronated grip, palms facing away from you, and hands about shoulder width apart. Let your body hang, arms straight, and cross your legs behind you.
Start the movement by drawing your shoulder blades together and continue by pulling your chest to the bar, using your back. Keep your shoulders down and neck relaxed the entire time.
Return to the starting position by slowly lowering your chest away from the bar until your arms are fully extended.
Pause and repeat.