Catherine Zeta-Jones credits ‘constant love and respect’ for her 20-year marriage to Michael Douglas

Catherine Zeta-Jones has been married to Michael Douglas for 20 years – and she’s now spilling the secrets behind their lasting union.

The actress, 51, and actor, 76, tied the knot in late 2000. They share two children: son Dylan, 20, and daughter Carys, 17. Douglas is also a father to son Cameron, 42, from his previous marriage to Diandra Luker.

"My husband is 25 years older than me; that’s not a secret," the star told WJS. Magazine on Monday. "With any relationship, it wouldn’t be normal if there weren’t any ups and downs. The constant is love is respect. We’ve never, ever lost our sense of humor, and we enjoy each other’s company."

Zeta-Jones emphasized that the two "have a lot of fun together."

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"My husband and I spend a lot of time together because, unlike so many couples, we’ve never had a 9-to-5 job where it’s consistent," she explained. "We’re either on or we’re off. I’m really working 16 hours a day, or I’m not. He’s doing the same, or not. So we’ve had in our relationship huge amounts of time where we’ve been just us. We lived on the island of Bermuda for 12 years bringing up our kids. We respect each other’s space, and our humor is just long-lasting."

Back in 2020, Douglas shared an audio message on Instagram detailing how he met his now-wife.

It all began when he attended a screening of the movie, "The Mask of Zorro," one of Zeta-Jones' breakout roles.

"I'm watching this movie, I go, 'Wow, who is this girl, she's incredible,'" Douglas recounted, and his friends told him about the actress, who was then an up-and-comer.

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"A month later, I was at the Deauville Film Festival. ... I see on the schedule that the next day at the festival, they're going to have 'Zorro' there," he recalled. "So I asked my assistant: 'Can you find out if Catherine Zeta-Jones is going to be here at the festival and if she's coming alone? And if she is, can I have a drink with her?'"

The Oscar winner's assistant came through and set up a rendezvous for the two.

"The next day, she arrives with Antonio Banderas and Melanie Griffith, and I have a drink with her and it was everything I hoped for, then she invited me to dinner with her company, I'm thinking, 'I'm looking good, this is looking good.'"

After dinner, the actress had to hurry off to another engagement, but Douglas told her that he'd be at the bar later if she wanted to join him again.

"Sure enough, I must have been batting one thousand, because, after the movie, I'm sitting at the bar, and like 'Laurence of Arabia,' this mirage comes through the lobby and it's Catherine Zeta-Jones," the "Ant-Man" actor reminisced.

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The two enjoyed a bit more time together before Douglas hit Zeta-Jones with a bold line.

"I'm going to be the father of your children," he told her.

"She looked at me and she said, 'I've heard a lot about you, I've heard a lot about you, I guess it's all true, good night,'" Douglas remembered. "And she left. She left early the next morning and I thought I completely had blown it."

All hope was not lost, however, as they eventually "made contact" again, and, as Douglas put it, "the rest is history."

Fox News' Nate Day contributed to this report.