A friend of mine told me it was his birthday. He didn’t seem all that thrilled.

“I’m 55,” he said, sighing.

“Congratulations,” I said.

“Yeah but now I don’t matter.”

“What do you mean?”

“Well, I keep hearing about these TV and radio networks, how they only really measure the ratings of people aged 25-54. Now that I’m 55, they don’t care what I think.”

I resisted the urge not to console him, but to tell him they stopped caring what he thought a long time ago.

We live in a youth-obsessed culture. You know it. I know it. But nowhere is it more evident than in the decisions being made on what we watch and hear.

Take the recent gathering of TV critics in Pasadena, for instance. When NBC President Jeff Zucker talked about his network’s reality TV programming including “Fear Factor,” in which contestants lie in a pit of rats, or “Spy TV,” in which an unsuspecting man might be caught kissing a woman who is actually a man wearing a wig he deflected criticism by saying that the shows were geared for the 18- to 34-year-old crowd and the critics were too old to get it.

These viewers “have grown up on the X-Games rather than the Olympics,” Zucker said, “and O.J. Simpson and Monica Lewinsky as entertainment.”

Oh.

In other words, they’re ruined already.

Of course, that’s not how the TV networks see it. They love these young viewers. More and more reality shows (and many more are coming this fall from all the networks, not just NBC) are geared toward younger and younger audiences. Why?

Because they’re gullible.

Not the kind of gullible that makes them believe that buff, gorgeous people who gather in the Australian outback are actually there to test their inner strength and not to get discovered for their own TV series.

No, a different kind of gullible. The gullible that watches a TV commercial about toothpaste and actually thinks, “Hey, I should buy that stuff.”

And that’s what this is all about. That’s the whole thing. The whole war over quality TV. It all boils down to this.

Young people, advertisers believe, are willing to change their beer, their soft drinks, their blue jeans or their shampoo if they see a convincing enough commercial.

Meanwhile, old people meaning, in some cases, people over 35 have already made up their minds. They are not likely to buy a Pepsi just because Britney Spears is popping out of her halter top.

The truth is, it’s not being old that makes us obsolete.

It’s being smart.

Of course, if you’re smart enough to know one deodorant isn’t much different from the other, you’re also smart enough not to laugh at people lying in a snake pit or trying to tempt one another into a hot tub.

And you’re smart enough to spot a snow job by a TV executive.

“We’re proud these are compelling shows and people are responding to them,” said Scott Sassa, NBC’s West Coast president, when asked about his reality programming.

Come on. Who’s he fooling? How can anyone be proud of “Fear Factor”? Why don’t they just say what they mean?

“Boy, are we happy! We found enough gullible young people who are willing to watch this junk to please our advertisers! They’ll be making money hand over fist!”

That might not be admirable, but at least it’s honest.

Then again, honestly is one of those archaic concepts that is followed only by the tribal elders in our society.

You know, people in their 40s.

Mitch Albom is the author of the bestseller “Tuesdays With Morrie.”