What is the rational, or most rational, response to finding out you're about to die? Not just to mortality, but that there's little more you can do in your life, and you're soon going to be, or are, dying? What would atheist existentialists say?
There is this from Nietzsche: that it doesn't (his interpreter claims) matter at all.
Nietzsche and the Becoming of Life, edited by Vanessa Lemm, p243. But does the dying man's attitude tell us anything about how we should live with the thought of death? Heidegger says that we should relate to our death as our own most possibility. Does that change if there's nothing, or very little, left we can do? Does it matter if one responds with despair, does this show we've somehow lived wrong? Or could that be a good, absurdist, response?
I would like a response from any of the major so called existentialist philosophers, rather than e.g. a Buddhist, which has its own stackexchange where I may ask the same question.