My sister and I were appointed as enduring attorneys for financial and health matters by our brother when he developed younger onset dementia. He also completed an advance health directive with assistance from his GP. The fact that he had done this was agreat help when we had to make a decision about whether he should have a major operation related to his bowel cancer. Although he could not express his wishes at the time, we felt confident that he would have wanted the surgery if he could continue to have a reasonable quality of life.
Being an enduring attorney can involve a lot of practical things like paying bills but it can also involve making important decisions about another person's care and treatment. This is not about taking over a person's choices – but really soul-searching to work out what they would have wanted. It makes it so much easier for everybody if the person has been able to make their wishes known while they still can. Our brother was starting to lose capacity, but he was still able to understand what was going on and he was able to let us know what was most important to him.