One of the problems with birthdays is that it becomes progressively more difficult to find famous people who hadn’t amounted to much yet when they were your age.

And every time you turn on the TV, there’s another pesky child prodigy on the news to remind you that, not only are you falling short, but your kids are, too.

Neither of my children played a Mozart violin concerto at age 4. OK, I admit it, they never played Mozart in any fashion, even on the kazoo. They never even listened to Mozart, at least not voluntarily.

I suppose every parent has felt that sharp stab of envy when a friend — or even worse, an enemy — boasts about how their child just got a perfect score on the SAT, or won a national contest, or even was potty trained at 12 months.

But it’s even worse when you feel that you are not living up to your own expectations for how you thought your life would turn out.

No matter how rich and famous you are, there’s a good chance you thought you’d be even richer and more famous by now. Or if you’re rich and famous enough, you hate your thighs or you’re a closet alcoholic or your spouse is cheating on you.

Let me tell you something though: It’s never too late to make your life better.

When people sit around and moan that they’re too old to change, I can’t help rolling my eyes.

Colonel Sanders was 65 and had just gone through bankruptcy when he opened his first Kentucky Fried Chicken.

Peter Roget was retired and considered a little weird and creepy, what with all the word lists he kept making obsessively. That is until age 73, when he published his Roget’s Thesaurus, which used every one of his lists and is still in print today.

One of my favorite authors, Laura Ingalls Wilder, did not publish her first book until age 64 and kept writing her “Little House on the Prairie” series until she was 76.

Finding joy

I wasn’t quite that old, but I quit a lucrative job in the entertainment industry in my 30s to become a newspaper reporter — a fairly strange thing to do — making $300 a week. Because I’d always longed to write, and everything else seemed like failure by comparison.

It was hard. I had to buy all my clothes at the Salvation Army. I lived on Top Ramen and frozen burritos. I had to work 12 hours a day with a bunch of young kids fresh out of college who didn’t even know who Crosby, Stills, Nash & Young was. I had an editor who screamed at me for my lack of knowledge until the veins popped out on his neck.

But I did succeed in becoming a writer, as evidenced by the fact that you’re reading this right now. And, believe me, these days especially, I don’t make much money but my job is pretty darn sweet.

The reason I succeeded was emphatically not because I’m more talented than other people. Believe me, I’m not. I just had tremendous determination to succeed, and the willingness to learn and take criticism. And that doesn’t go away with age.

My grandfather owned an auto repair garage all his life. He sold it when he retired and added a room onto his house to have a little business that he’d always enjoyed — restoring antique guns.

To everyone’s surprise, Grandpa ended up making more money from his little gun shop than he ever made fixing cars, because he did it with passion, and low overhead.

He even beat cancer and kept going until his late 80s. I’m convinced it was because he was doing something he loved every day.

Occasionally, middle-aged women tell me wistfully that they wished they’d had children before it was too late.

Hello. I adopted my two kids when I was 46 years old, due to the fact that I had spent all those years being busy changing careers.

As the cartoon says, “I can’t believe I forgot to have children.”

Yes, it was bloody hard chasing two little kids around when I was already starting to feel a little creaky in the joints.

But what was the alternative? Sitting around making doilies? Since I’m not married, adopting kids gave me an instant family.

Sometimes, it’s been hell. I don’t put everything that goes on in our household into my column. That would violate our privacy. Kids are messy and problematic, and make you cry.

They are also the source of nearly all the joy in my life today.

And the reason I get out of bed and start working every morning.

And, hey, they’re finally old enough to do some real chores around here.

Whether or not you have kids or like what you’re doing with your life, I just want to tell you that you have so much more control over your circumstances than you think. And it’s never too late to get out there and do it.

I’m thinking about Nelson Mandela right now, because I’m writing this just after he died.

Think about him. Imprisoned for 27 years. Then he became not only the president of a country that formerly wouldn’t even let him vote, but also a leader venerated around the world.

“There is no passion to be found playing small — in settling for a life that is less than the one you are capable of living,” he said.

And, “It always seems impossible until it’s done.”

Try to do one thing that’s impossible for yourself today.