One arm chin-up

Stand facing a pull-up bar with your feet shoulder-width apart. Reach up and grab the bar with an underhand grip, with one hand gripping the bar and the other hand holding your wrist for support. Hang from the bar with your arm fully extended, keeping your body straight and your core engaged. Pull yourself up towards the bar by bending your elbow and squeezing your back muscles. Continue pulling until your chin is above the bar, then slowly lower yourself back down to the starting position. Repeat for the desired number of repetitions, then switch arms and repeat.