"I thought, Woah, beautiful woman standing in front of me," says Henry Winkler

It’s been over four decades since Henry Winkler first laid eyes on his future wife Stacey, but the actor can still recall the day in vivid detail.

“She was wearing purple parachute pants and she had red hair and without her even saying a word, I thought, Woah, beautiful woman standing in front of me,” Winkler, 73, who met Stacey in 1976 when he was starring as The Fonz on Happy Days, tells PEOPLE. “I came back to the store the next week and was there. And within 10 minutes, I learned how strong she is.”

Continues Winkler: “I said, ‘Would you like to go for a soda? I just have to make a quick stop to buy a wedding gift.’ And she said, ‘I am not a gift service!’ But then she changed her mind and we went across the street and had ginger ales.”

Henry Winkler with wife Stacey
| Credit: Pamela Littky
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Within weeks, Stacey and her then 4-year-old son had moved in with Winkler; they wed in 1978 and went on to have two more children: Zoe, 38, and Max, 35. Stacey stood by her husband as he navigated his career post-Happy Days and was by his side when he won his Emmy last year, for his critically acclaimed role on HBO’s Barry.

“The most wonderful thing is to really be able to grow with someone,” says Stacey of their 40-year marriage. “We’re not the same people we are when we got married. But certain of the tenets you hold dear are still intact.”

Admits Stacey: “It does take work. There are glitches in the road, and you get a little off kilter, but if you have the ability and the stick-to-itiveness based on love, then your friendship and your relationship only gets better.”

Says Winkler: “We enjoy fly fishing together. We enjoy grandchildren together. We enjoy going to the movies together. We truly enjoy each other every day.”

Credit: Pamela Littky

And becoming grandparents together has been a shared joy.

“My favorite part is watching them,” says Winkler of his five grandchildren. Adds Stacey: “And as a grandparent, you always have a fall guy. ‘You want a hot fudge sundae? Let’s call Mom!’ But they work us so hard!”

It’s all worth it, says Winkler. “I’m thrilled to be on this earth, I’m thrilled with my family and I’m thrilled to be doing great work.”

Barry airs Sundays (10 p.m. ET) on HBO.