Viktor and Milan talk it out...

"We can never know what to want, because, living only one life, we can neither compare it with our previous lives nor perfect it in our lives to come.
There is no means of testing which decision is better, because there is no basis for comparison. We live everything as it comes, without warning, like an actor going on cold. And what can life be worth if the first rehearsal for life is life itself? That is why life is always like a sketch. No, "sketch" is not quite the word, because a sketch is an outline of something, the groundwork for a picture, whereas the sketch that is our life is a sketch for nothing, an outline with no picture.
Einmal ist keinmal... What happens but once, says the German adage, might as well not have happened at all. If we have only one life to live, we might as well not have lived at all."
Milan Kundera

"Only under the threat and pressure of death does it make sense to do what we can and should, right now. That is, to make proper use of the moment’s offer of a meaning to fulfill—be it a deed to do, or work to create, anything to enjoy, or a period of inescapable suffering to go through with courage and dignity…Live as if you were living for the second time—and as if you had acted the first time as wrongly as you are about to act now. Once an individual really puts himself into this imagined situation, he will instantaneously become conscious of the full gravity of the responsibility that every person bears throughout every moment of his life—the responsibility for what he will make of the next hour, for how he will shape the next day…facing the transitoriness of human existence—how is it possible to say yes to life in spite of death"
Viktor Frankl