Quit trying to shoot groups for now! Just shoot one arrow at a time, with the very best form andthe very best concentration you can muster.Pull it, shoot again. When youfeel likeyour concentration is slipping or you're getting too tired to maintain good form, quit for the day.

Get away from that target as much as you can too. Get out in the woods with some judo points and just do some plinking / stump shooting. This is supposed to be fun, not an exercise in frustration.