Over the holidays, I reached a personal milestone.

To put it another way: Oh, my God, I’m in my 50s.

I had a great birthday, but it still was a birthday. Oh, my God, I’m in my 50s.

Okay, I’m overstating the terror a bit. Quite a bit, actually. Entering a new decade always entails something of a paradigm shift, but by the time you get to your sixth one, hopefully you’re used enough to that kind of change that it isn’t a huge seismic calamity. It’s a marker, but a relatively unimportant, transient one.

Of course, that isn’t always true. When you’re a kid, a birthday is a big deal; it’s your own personal holiday and a chance to get swag on a day when nobody else does. It’s less a marker of time’s passing than a fun little personal punctuation mark in onrushing childhood.

My own birthday was kind of an oddly timed punctuation mark because it comes three days before the major event of the kid year, Christmas. That actually was fortuitous; people always assume the timing meant I got screwed, that I got a lot of two-fers. Actually, the timing was great. I made out like a bandit. I remember that on my eighth birthday, between the two holidays I received something like $40, in addition to gifts. An 8-year-old with $40 is Donald Trump, believe me.

It did start to suck, however, by the time I had my own family. We always spent so much on the kids that there wasn’t much left over for me, let alone time to celebrate during the late-holiday madness. I’d get my free dinner at a local restaurant and a pecan pie, but there wasn’t usually much in the way of presents. Oh, well.

And as I approached middle age, the time-marker aspect became more important. It sort of reached its nadir on Dec. 21, 1988, the night before I turned 30. I recall sitting in the kitchen of my childhood home, alone, when it hit me like a ton of Geritol: “Oh, my God, I’m going to be in my 30s tomorrow.”

In a way, it was a uniquely baby-boomer moment. I am, after all, a member of the “don’t trust anybody over 30” generation. It occurred to me, sitting there at the table where I’d eaten so many boyhood dinners, that as of about 7 a.m. the next day, I’d no longer be trustworthy. I had visions of waking up the next morning bald, paunchy and conservative Republican. I figured I’d celebrate my birthday by yelling at the neighborhood kids to get off my lawn and settling down to an evening of Lawrence Welk (hoping that he’d play his absolutely kick-butt version of “Stairway to Heaven”).

Being a baby boomer didn’t help with the whole getting older thing. As a member, albeit a late one, of the most obnoxious, self-involved generation in history, I suffered from the same malady as my older boomer brethren and sistren. I’ve been a perpetual Peter Pan of sorts, although I’ve less refused to grow up than not believed I’ve grown up. Even though I look in the mirror every morning and see grey hair, increasing wrinkles and eyes that have seen a bit of the world, I have a really hard time thinking of myself as a grown-up. There are times when I look at my grown-up world with its grown-up responsibilities and think: Wow, I live in a grown-up world with grown-up responsibilities. I’m playin’ for real stakes here.

What most adults tend to forget, though, is that real kids play for real stakes in their own real-kid world. To a 6-year-old, that bully on the playground is every bit as terrifying as the sadistic, bullying boss is to that kid’s 35-year-old dad. In fact, I once worked for a guy who was a playground bully writ large, and it amazed me how very similar the dynamic was. Getting beaten up on the playground may not last as long as being fired, but to a little kid it’s every bit as traumatic, if not more.

But that’s all in the past. I’m now a man deep into middle age. I long ago passed the point where I was closer to the beginning of my life than to the end. I’ve always sort of fixated on getting my biblical threescore-and-ten for some reason, and I realized last week that now gives me a target date of Dec. 22, 2028.

I long ago surrendered many of the things of youth. At least, I hope I’ve given up the stupid parts, like killing off brain cells in the firm belief that there are enough replacements available. But there are other things of youth I just can’t give up. Whenever I’m in Target, I still sneak over to the toy department to check out the action figures. I recently was introduced to graphic novels, and I’m thinking I may develop, or renew, a love for comic books. At the very least, it makes me look relatively hip.

But maybe, just maybe — and I realize this has the aroma of rationalization — holding on to a few of those things of youth, even the stupid, insignificant ones like perusing action figures, is a way of holding back creeping old age. As long as I can look at a four-inch plastic Batman and hear deep in my mind a 7-year-old voice say, “Boy, that would be cool to have,” maybe I’ll never be entirely elderly.

Still, I realize that I’m not going to get any younger. So let me just say this:

You kids stay off my lawn.