In Texas, a living will is a "Directive to Physicians and Family or Surrogates" and allows you to put in legal form your end of life decisions. The Directive divides end of life decisions into two categories, one if you are facing eminent death and the other if you are in a persistent vegetative state. No matter where you live, you need to consider these two categories.
What kind of medical treatment do you want if you have a very limited time to live? Do you opt for comfort? Do you choose a last ditch effort at treatment to prolong your life? There is no correct answer. While I would choose comfort and not a life prolonging treatment because I am a Christian and convinced that death is a door to better existence, I do not believe that should be everyone's choice. I fear that too often societal pressures make it seem that we are misusing resources and somehow wrong to fight for every minute of life. I believe this becomes more prevalent as we age, but quality of life, not age, should be the deciding factor. For this reason, I think you have to consider this choice long before you are enmeshed in medicine's clutches.
I know people who have advanced directives that make it clear that they wish to stay alive at all costs. Others I know do not want hospice. However, I believe the vast majority of people who bother to execute a living will do so because they do not want their life prolonged by artificial means including artificial nutrition and artificial hydration. I find that in the absence of a living will or other clear direction, most families opt for all life prolonging measures.
More difficult for me is to decide what you want done if you are in a persistent vegetative state. As I understand this state, you are never expected to regain consciousness, but you will not die if you are given artificial nutrition and artificial hydration and personal care. This is difficult because here we confront the imperfections of science. In extreme cases, there is no doubt that the person will never recover, but we all know cases where there has been a seemingly miraculous recovery. My choice would be no artificial nutrition and no artificial hydration: let me die. I do not think that is the correct choice for everyone. Only an individual can make that choice for themselves. In the absence of a directive or other clear directions, every effort should be made to keep someone in a vegetative state alive. Again, make your wishes known in a living will.