I think you're taking it too literally. Let's say you are 60 years old, in perfectly good mental health, and are diagnosed with a terminal illness and will not live longer than a few months.
I rarely do this exercise, but it has been helpful at times. It's a lot simpler to do if you're older (late 30's or higher). You can look back at your pursuits over the last few decades and can actually see things like "Oh, I've been learning new programming languages for so many years now. How useful has it been?" If I extrapolate for another decade or two, will I be happy at age 50 or 60 with the outcome if I continue with these activities?
I have many more pursuits than I can do in this life. When you're younger, you usually don't limit your options because you feel you have a lot of time. When you're 40, you can easily say "I've been doing this for 20 years. If I don't change/prioritize, I'll soon be at 60. Is this stuff worth doing at the expense of other pursuits?"
This year I ticked off two bucket items. I had been putting them off for too long. IMO, it is worth thinking that way.
Being lucid at one's deathbed is already a positive situation that might simply not happen under some circumstances.