I was swapping dad stories with a friend and laughing hard. Then my friend got quiet and said something that hit me hard.

“God, I wish my father was still alive.”

I’m one of the luckiest sons on earth because my dad is healthy, and I pray he stays so for a good long while.

But I wake in the middle of the night sometimes — for a few moments, I don’t remember where I am in time. Am I 20? 30? 70?

And I worry. I worry about my mother and father. I have dreams about them being ill, hurt or in need of my help. Sometimes I dream that they are gone from me, and my anguish is overwhelming.

But as I come around, I realize I am 53 — that I’m extraordinarily blessed because everyone in my family is well. I feel like I’ve just won the lottery.

My sense of time is keen in the middle of the night. It was just a few heartbeats ago when my dad’s mother died — 43 years ago, the same night that Roberto Clemente’s plane went down as the Pirates great delivered food to the poor. I was 10 years old then, but it wasn’t so long ago at all.

My father’s father died in 1937 and I used to think that was an eternity ago. But it wasn’t at all. My dad’s dad was an accountant for the Mellon family. He also helped the family run the Rolling Rock horse races, held in the autumn. It was rainy that week and he had a cold. The cold turned into pneumonia and he died at 34 when my dad was 3 — only 25 years before I was born.

At 53, I’ve come to understand the fleeting nature of time and how it is intent on robbing from me the people I hold dear. I know now that my dad was once a young man. There was a time he felt he had an eternity before him, and suddenly he’s 81. I know now it’s just a few blinks in time before I’ll be where he is. And I know I’ll wake one day just as he does now and he will be gone.

Lately I’ve been overcome by strong feelings of nostalgia for my father. I remember when I was 5 and he would sit in the cool of the cellar on Saturday afternoons. Mr. Bennett, our neighbor, would be there. They’d watch the Pirates while shooting the bull and knocking back a couple of Pabst Blue Ribbons. It was my job to go get refills. I’d pop the caps, then lug back the 16-ounce returnables. My reward was a sweet sip of the ice-cold brew, a taste that still summons from me the security and happiness I knew on those Saturdays.

I remember when my dad got home from work every night. He worked as much overtime as he could to pay the bills, and when he finally got home, I’d hear the door open and his big foot hit the floor with a boom. He’d go downstairs and pour himself a beer, then seek out my mother and kiss her on the lips — he did this every single night for more than 40 years.

My dad has no idea what impact he has had on his children, how small gestures and memories evoke such powerful affection and respect. He knows we love him, but has no idea how much. Or how much pain we will know when it is our turn to say, “God, I wish my dad was still alive.”

But for the moment, I am grateful for my good fortune. For reasons I can’t comprehend, God keeps blessing my family. My father is still here and doing well. And all of us are lottery winners.

Tom Purcell, author of “Misadventures of a 1970’s Childhood” and “Comical Sense: A Lone Humorist Takes on a World Gone Nutty!” is a Pittsburgh Tribune-Review humor columnist