Matt:
First off....relish those feelings. They're awesome....and if they ever leave me....I'll quit.
This is my fourth yr bowhunting (coming up). I've been fortunate enough to secure some really fertile grounds....and I see MANY, MANY deer, every year. In 2005...I had a group of does under me and one small buck. I never reached for the bow.....but i was standing. I remember having to prop my righ tleg against the tree because it was shaking so bad. And I wasn't even gonna shoot. If I could bottle that feeling and sell it....I'd retire, tomorrow.
PGA TOUR Pro Tom Watson said once....that there is no substitute for putting yourself "in the arena". You don't know how you're gonna react (totally) unless you put yourself in that position enough times to learn to deal with your emotions/anxieties. I still get those feelingsa lot....but I'm getting better at controlling them (which is THE fun part).
I think it was MOTOWNHONKEY who told me to pick a spot on a deer AS SOON AS I knew it was one I wnted to take. Never let your eyes leave that spot when you're looking a that deer (you're gonna need to look elsewhere, sometimes, .....other deer.....pick a shooting lane.....pick a place to draw when their head's behind a tree....etc....), but when you look at that deer......focus on one small area (very small). It's helped me to control myself in those situations a lot.
Good luck with it....
Oh yeah....I'm 43.