Being able to hold your draw is one of the biggest factors with bow hunting. If you draw too early, they may bust you or in your case you may have to hold too long. I have also been in your situation, 65# 60% letoff, for 5-8 minutes. I have learned how and whereto setup my stands from this to help avoid it. Thus giving me the chance to draw later while the deers head is behind a tree or while the deer is in the brush. This eliminating the long painful hold. Look at the area youre hunting, is there anything you can do different for your setup? Can you turn your stand so it facces a group of trees where the deer are comming through? Try changing your stand setup. Again the most important factors are to practice and to keep your muscles warm.