My father-in-law smoked for a long time. Then right before I married his daughter, he and his wife both decided to quit smoking. He hadn't smoked in 20 years, but the damage was already done. He also was on dialysis. In fact, for 15 years. When he got sick, the doctor told him he would need surgery on his lungs, but there was an 80% probability, considering the damage that had been done over the years from smoking, that the surgery wouldn't work. It was then that he made the decision to stop his dialysis. Of course, the family and all his friends tried to talk him out of it, but he was 80 years old, a WWII veteran, and had lived a good life. There was no convincing him. He eventually went to a hospice and died peacefully. Right before the kidneys took him out completely, they sedated him so that he didn't suffer. That was his decision, even though no one wanted him to carry through with it.