“Inside every old person is a young person wondering what happened.”

Those are the clever words of British humorist Terry Pratchett, who couldn’t have explained the aging process more succinctly.

I know his words are true because I turned 60 this week.

It’s a heck of a thing to have burned through six decades already. If I’d known 60 years would go by so fast, I would have taken worse care of myself.

Time is a humbling thing.

I know now my greatest accomplishment — aside from an uncanny ability to catch grapes in my mouth no matter how far or high my friends throw them — was becoming a bouncer at the legendary Rathskeller pub at Penn State.

When I was half this age, I was certain I knew everything. I was cocky and brash and incredibly wrong.

Now, I realize I know very little, but the things I do know, I know well.

I know that fame is a waste of time — and excess wealth, too — as they bring with them more problems than either are worth.

You don’t who your friends really are until your money is gone. And if you ever do anything stupid as a famous person, social media will broadcast it all over the world.

Several studies have been done on the subject of happiness. Having just enough money to save a little for a rainy day and go out with the love of your life a few times a month is all the money you really need.

It’s friends and loved ones that bring us real wealth.

It’s the laughter we can only enjoy with our closest friends — people we know we can count on no matter how difficult our lot becomes.

It’s the love we enjoy from our closest family members, friends, and lifelong spouses and partners — the people we attend weddings, holiday events and special occasions with — all of our most memorable experiences.

And it’s not just people.

Why I waited until the age of 59 to get another dog — last having one as a child so many years ago — is possibly the most bone-headed decision I ever made.

Somebody said God removed the wings from pets like my best buddy Thurber, so that nobody would know they are angels.

This guy makes me laugh out loud every single day — something I didn’t realize I was failing to do until he entered my life.

When we are young, we dream of big houses, and we hope to impress total strangers.

As we grow older and wiser, we realize none of that matters. We realize that time is going by way too fast and that every single moment is precious.

I was sick as a dog with a nasty flu weeks ago and, brought to my knees, I went through a paradigm shift.

I decided I never want to waste another healthy moment.

I started eating healthier than ever. I exercise daily. I go for walks with Thurber.

I turn in at a decent hour, so I wake refreshed at 5:40 every morning ready to dive into the new day.

All I want to do now is write well, read great literature and learn how to love better, give back more, laugh harder and spend every moment with people I love as though it were the last moment I had to live.

Maybe it’s time to alter Pratchett’s clever quote:

“Inside every old person is a wiser person trying to make great things happen with whatever God-given time he has left!”

Tom Purcell is a Pittsburgh Tribune-Review humor columnist and is nationally syndicated. Send comments to Tom at Tom@TomPurcell.com.

Views expressed in this column are those of the writer only and do not necessarily represent those of the newspaper.