Today's a full-on back attack starting with the warm-up, where you'll crush a set of 50 pull-ups. Of course, you can break those up however you see fit, but make sure to get them all in. Every single rep counts.
If you can bust them out pretty easily and are looking to add a bit more challenge to your end-of-the-day workout, increase the intensity. Strap a weight plate to your waist or have a buddy place a dumbbell between your feet for some added resistance on the way up.
If you're newer to the art of the pull-up, do machine-assisted pull-ups, or better yet, use a light resistance band to help give you that initial push.