That shoulder burn is one of the best feelings in the world. If you've never felt it, you're about to get your world rocked.
Be smart about your weight selection. You have a lot of reps and a lot of sets. That doesn't mean you should go light, it means you should do all the reps with the heaviest weight possible. Choose a weight that will be a bitch to do for 20 reps, but you know you can do it. If you find yourself gassing out at five reps on the first set, you know you've gone too far.