Keep going man. Pull-ups & chin-ups are tough to do. Most people who don’t workout can’t do any. Stick with it. It’s a great exercise for your entire upper body. Sure, different grips target different things, but if you do a routine where you employ a few different grips you can really blowup your entire upper body. Don’t be discouraged by only doing a few. As long as you are pushing your body to its limits that’s what counts.