It seems strange to think that human beings cannot live their lives without thinking to themselves that there must be some sort of eternal retribution at the end. That at some point we are rewarded for our hard work and staying alive as long as we have, granted that we have lived "good," "worthy" or "meaningful" lives. But I can't seem to bring myself to actually believe in an afterlife and furthermore, I do not think I must necessarily frame my action as some sort of evaluable experience that will be judged after the fact. Unamuno points out that there is no truth that is not subjective, that we must all give our lives meaning, and that believing in an afterlife motivates us to make meaning in the world. While I cannot genuinely belive in an afterlife, it seems that my mortality and the finality of my life is what drives it and gives it meaning.
It is only reflectively that one begins to posit a meaning for his/her life, not actively. Thinking about some abstract eternal return may be helpful for some. But my own temporary existence on this earth and knowing that nothing will become of me after death (I will be dead afterall) seems to be an objective truth I cannot deny. And while I do not know for sure what will become of me upon my death, I don't think that an afterlife is going to help make my life anymore meaningful. In this way, Athiest Existentialism seems to make more sense to me than Religious Existentialism as I think it gets at the heart of the problems of human existence, that we are powerful meaning making beings, but that we are one of billions of those beings who are born and die everyday. It is the intersection of my particularity of being situated in the world and my anonymity of being just another being that is meaningful, not some sort of eerie, dream-like relationship to the world in which I must give a reason why I have lived at all when I wake up.