Start in the dead-hang pull-up position. Instead of pulling straight up, pull to your left side, touching the top of your left pectoral to the bar. Descend under control, then do the same thing to the right.
You can also go side-to-side for two reps before descending: pull to the left, hold at the top, transition to the right, then lower yourself. Start the next rep by pulling to your right.
They say you can't out-train a bad diet, but you CAN out-train a moderate one. Here's how to work out and eat so that you can still make progress without strict dieting.
This is a great exercise that builds you delts while also protecting joint integrity. The cable is attached at the bottom of the handle, so you'll be pushing up, not pulling down.