I think this song is about anxiety (I talk of six while forgetting five; can't even taste if my food is alive; I guess I'm always tomorrow-bound), and how it feels when you are always worried about things that aren't even real (staring down some invisible fear). In the end, he realizes how tiring it is to be always worried about what's coming next, but he had spend all his life without actually living the moment and now is too late, because he's already underground