When pain is so great that there is nothing left for you, your only choice is to be pain. When you become pain, there is nothing left to hurt, it is just pain being pain. That is pure acceptance.
If you are so unfortunate as to have to become pain in order to endure pain, then you have already suffered immensely. As you learn to endure your pain with awareness and focus, you can bring yourself to a point where you forget about yourself. There is only the pain, a small pin prick in a vast universe. In order to come to that point, you need to focus your awareness directly at the pain. Don’t look left or right or up or down. Your pain is your guide, watch it as though it were a snake poised to strike.
If you focus on the story of the pain or the future of the pain and you wish that it weren’t there, the pain will continue to be unbearable. If you enter your pain and become your pain, you will learn its lesson and its wisdom will be yours to share.