To add onto what Derpderp said , Someone I know mentioned this as well but about his birthday. "I'm just getting closer to death" Well in my opinion every second closer to dying, Is a second we lived. In my mind it's the fact that I got that extra second of living that makes me appreciative, and outweighs the inevitable of death.
Going with that Idea, I think then that things like, Our Birthday, And New Year's Day, Ect... are traditionally celebrated to be around those you love, and truly in that one moment be thankful for what you have. It's just that now in such an artificial world we want celebration and frills that are unneeded.