I used to get tore up back in the day. Admittedly, I still get a little riled up, but it's nothing like it was when I was a rookie. I believe experience in both observing, and in killing deer, is the only way to learn how to overcome it. If I stop getting excited when I have a chance to kill a deer, I'll stop hunting. I also believe you can practice battling for the "fever" by getting your heart rate and breathing up during practice. I do this and I think it helps. After a while, you develop an auto-pilot that is very beneficial in the moment of truth!