I just marked one of those birthdays where the odometer flips over two digits, the kind of milestone that reminds you nature is relentlessly serious about that ashes-to-ashes thing.

You get three big birthdays in life: 16, 21 and anything ending with a zero. Those first two come with long-anticipated freedoms; the others are merely countdowns to entering a dimension of diminished sight and sound.

While I enjoy personal fossilization as much as the next guy, I continually nag myself to avoid certain age-appropriate behaviors.

I do not purchase health remedies hawked on cable TV, for example, though I am just dying to order the “WaxVac,” which would free me evermore from the potential danger of sticking Q-tips so far in my ears that they’d dent my brain. That would be one less thing to worry about.

I do not spend gobs of time regretting the sins I have done unto others, because most of them are either dead now or can’t remember what they had for breakfast much less me snarling at them decades ago about something that didn’t matter anyway.

Most of all, I resist the temptation to smother any interesting conversation by jumping in to report how we did it back in my day, which was the Middle Cenozoic.

Strong is the desire within me to share the wisdom of past epochs, but certain is my knowledge it will get me invited to no dinner parties. I will not geeze. This is my firm policy.

If I were a weaker, less disciplined person, I would give in. I would clear my throat and dive in with the preamble, “I can remember when …” and proceed with:

• You wouldn’t dream of buying car insurance from a lizard.

• Green meant “go” instead of “I’d better hurry and finish this text.”

• You could uncap a medicine bottle without getting the neighbor’s kid to come over to help you.

• You’d make fun of your dad, who called the Frigidaire an “icebox.”

• Bert Parks, Guy Lombardo and Dick Clark were really old and Mick Jagger wasn’t.

• People argued over whether there should be silent prayer in schools rather than armed guards.

• You’d buy a used car, not a “certified pre-owned vehicle.”

• “Multimedia” meant you got the afternoon paper, too.

• Perfectly sane people did not entertain the notion of tolls on Interstate 77.

• Michael Jordan’s name was synonymous with winning.

• People replied, “You’re welcome” rather than “No problem.”

But I won’t. No geezing from me. I’m still in control of my senses. Consider yourself lucky.