The hardest thing for me to do in trap and skeet is not let my mind wander.
My mentor used to say you have to concentrate for only about 2 or 3-seconds per target. That equates to about 4 or 5-minutes in a 100-taget event. Doesn't sound too hard, does it? It's easy for your mind to wander while the others are shooting, the hard part is getting back on track when you're up.