I'm with you about our bodies being self-repairing provided we don't get in the way, and we feed it properly.
I personally don't believe there is a "point of no return". I've heard some amazing stories and miracles do happen. I will say that my belief that there is always hope is challenged many times, and many times I almost lose faith. But I'm still alive, following my intuition, and trusting that God is going to guide my way.