I would like to offer a concrete example of my stoicism and rationality:
I think birthdays are stupid.
I mean, it's really all arbitrary. The earth year is merely a coincidence, depending on the mass of the earth and the sun and the constant of gravitation (although, I supposed I could use the anthropic principle and say that any planet years would be roughly equal, to achieve life sustaining conditions). While this is important for agriculture, there is no reason would would celebrate this for our birth. And what's more, it's not even correct. We are celebrating our birthdays every 365 days, when it actually takes 365.242199 days for the earth to go around the sun. That means every year, we are celebrating earlier in earth's orbit - a whooping 387,483 miles from where we celebrated last year. Add in leap years, and counter leap years every 100 years (except the counter counter leap years every 400 years), and that imprecision just builds up.
And what's so important about our piece of rock circling a giant ball of gas? Why not use the lunar year - so we have birthdays every 27.3 earth rotations? Or the galactic year, which makes it's round once every 250 million years? Another nice and arbitrary one is the Halley year - which goes by the orbit of Halley's comet (who wasn't even the first person to observe that lump of ice).
We can even go the other way, and not just celebrate birth days, but also birth months (30 days of partying!) and birth seconds (make a wish! too late). And when you think about it, birth seconds are much better for your ego. Think about it: 6,740,000,000/365.242199 = 18,453,508 people have the same birthday as you, while only 6,740,000,000/31,556,926 = 215 people have the same birth second. If you go down to birth nano-seconds, then you'd even be /unique/. Think about that.
Oh, and there's the whole business with half-birthdays (which I guess are okay), unbirthdays(which are awesome, if only because it appears in Alice's adventures), as well as decimal birthdays (which are just plain bad, because of the additional arbitrariness of the decimal system. Really, people were arrogant enough to just use their number of fingers as the base?).
Personally, I think if you're going to celebrate someone's life, just celebrate it whenever, I think I've listed enough birth-[time unit]s that you'll have reasons to party for the rest of your life. So why not just enjoy your day, take pleasure in being alive, and be glad that other people are suffering for 364.242199 days of the year?
Now, if you're happy and you know it... clap your hands!