I remember my father summarizing a scifi book to me once where humanity created a super computer that calculated for them the meaning and reason behind existence of us and the universe. The answer was basically that, "There is no reason for existence, it just is" to which humanity just ended up in a state of depression as if this were devastating.

At a young age I always thought that story to be more than a little retarded and that the meaning should have been an obvious one, that we make and define our own reason for existing. It seems that if there ever was some true meaning or reason for existence that it would take all flavour out of living more than there being no reason, because simply put it would mean regardless of what we want we'd exist for that specific reason.