Which is more important to you? Quality or Quantity? Do you have a living will that your family is aware of and will abide by? When will it be enough for you?
To me, quality is of the upmost importance, as, I am sure, it is to everyone. But how about your family? Are they going to abide by your wishes, are they bound legally to do so? And how do you feel about saying "enough is enough" and I don't want to live if I don't have quality in my life?
For me it is quality of life, not quantity. If at some I am incapacitated to the point that an acceptable level of quality can be maintained without burdening family, it is time to check out! I do not have it in writing yet, but I plan to do it.