I assume you are a hunter. If so, I've found that thinking about the release while executing the shot is the archery equivalent of the Animal House movie line, 'Whatever you do don't hit those trash cans". Well, we all know what happens in the movie.
If you can forget about the release and let back tension be a subconcious result of rather than a concious part of your shot, its easier to avoid problems in the field. Put another way, if you're thinking about your release hand or your back muscles you aren't concentrating on what you're shooting at. And you can only focus on one thing at a time. It might work at the practice bale under practice conditions, but not so well under hunting conditions.
For an excellent demonstration of how the focus/draw/shoot sequence looks in practice, check out the John Schulz video "Hitting'em Like Howard Hill" or some of the excellent Howard Hill shortfilms on this site. You might want or need to tweak the steps to fit your personal needs, but they are great tutorials of how to make the release (and the rest of your form) a more or less 'automatic' part of your hunting shot.