Never feel bad about passing on a shot unless you're getting to the point that you're beginning to miss sure things. I've passed on many shots that I might should have taken, but it's always to be sure than sorry. Like someone else said, keep practicing - and practice your quick shots at the range from hunting positions (standing, sitting, laying, etc.). When I say quick shot - practice slowly and only make it quicker as you can do that but still stay accurate - use a milk jug size target - so you can hit that every time. As you can do it quicker and quicker, you'll start to take those surprise shots in the field. Good luck and keep up the good work.