Fifty. The Big 5-0. Yep, in a few days I'll be there.

It's an odd age. When you're not wistfully reminiscing about your wild and reckless youth, you're looking ahead with relish to your retirement years when the kids will be gone and you'll be able to relax a little and reclaim a bit of your soul, maybe.

Right now, I can hardly breathe.

Birthdays long ago lost most of their significance, although they come in handy for justifying high-end purchases and eating cake. This year I have no purchases or celebrations planned. Birthdays seem so arbitrary. I mean, you don't really wake up on the anniversary of your birth a whole year older, just a day older from yesterday. And tomorrow you'll be still another day older. So what's the big whoop?

My doctor seems to regard reaching the half-century mark as some sort of milestone — can you say "colonoscopy"? — but someone explain to me why turning 50 is any more momentous than turning 51?

If this sounds like sour grapes, it's not. It's just that the older you get, the clearer things come into focus, even as your eyesight is failing. Silly little events such as birthdays don't matter as much.

There are many more telling ways to mark the passing of time. I was reminded of this during the recent Maui County Fair. When the kids were very young, we plopped them down on the train ride or the merry-go-round and got a bigger kick out of it than the little tykes did. A few short years later they're ready for the Super Sizzler or the swings. Then the fair is no longer a family outing because they'd rather meet their friends there and you're not invited. Just as well, because the days when you could stomach amusement rides are long past.

This year, the middle-schooler wanted to go with his friends at night and the high school senior didn't want to go at all. Kid stuff, she said.

Holidays follow a similar trajectory. A few days ago when I walked past the toy department at a discount store, already fully stocked for Christmas, it hit me that this would be the first year I wouldn't be buying any toys, except for maybe a board game or two. Clothes and electronic gadgets have replaced childish things on Santa's list.

But you mark time not only by your kids. Relationships follow their own calendar, and there are new jobs and work promotions, your first home, the trip to Europe, a dreaded medical diagnosis, the death of a parent.

Maybe birthdays are best used not as a celebration of passing years but as a one-day respite to catch your breath and take accounts.

And eat cake.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.