Here's what dad's Living Well says:
If...my physician certifies in writing that 1) I have an incurable injury, disease, or illness; 2) my death will occur within a short time; and 3) the use of life prolonging procedures would serve only to artificially prolong the dying process, I direct that such precedures be withheld or withdrawn...

This to me is clear...and it doesn't cover death by old age.

So, the moral is: Don't limit the conversations to terminal illness or heroic acts. Frankly, I believe that if I was reasonably healthy and being asked if I would expect someone to administer CPR if my heart stopped, then I would say "sure"...

This is VERY frustrating and very complex to me at a moral, spiritual, and relational level