Lori Loughlin Has Been Celebrating Her Wedding Anniversary on the Wrong Day for 20 Years! (Exclusive)

The 53-year-old actress also told ET the secret to her long-lasting marriage.

Lori Loughlin and her husband, fashion mogul Mossimo Giannulli, were so eager for their first wedding anniversary that they celebrated it two days earlier -- and have been doing it for the past 20 years!

ET's Deidre Behar sat down with the actress on Thursday, where she opened up about the secret to her long-lasting marriage, admitting that it clearly has nothing to do with remembering your anniversary. As Loughlin confessed, it wasn't until recently that she discovered she and Giannulli had been celebrating on the wrong day, thanks to Marilu Henner. 

"I was having dinner with Candace Cameron Bure and Marilu Henner, and you know, Marilu has that incredible memory," she explained. "Somehow we started talking about my elopement and I said, 'Yeah, we got up on Thanksgiving morning'... We had Moss' best friend and a minister meet us, and we got married at sunrise and then we went to Thanksgiving dinner and we told everybody." 

"Marilu happened to say, 'Oh, what is your wedding date?' And I said, 'It's Nov. 25, 1997,' and she goes, 'No no, Nov. 25 was a Tuesday... Nov. 27, 1997 that was Thanksgiving,'" Loughlin continued. "She was right! And on my marriage certificate, they had written Nov. 25 and that's what it says on my marriage license."

"So I called my husband, and I 'm like, 'Oh my goodness, we have been celebrating two days early!'" she said with a laugh. "So it's actually Nov. 27, 1997... I think we're going to make [our anniversary] a three-day festival now." 

After 20 years of wedded bliss, the couple definitely deserves the celebration. 

"Moss and I had both been married before, so we thought, 'Well, it didn't really work out well for us the first time around, so maybe we'll elope and see how it goes and tell people,'" Loughlin recalled of their decision to tie the knot. "We had talked about doing a wedding and we just thought, 'Let's get up and let's go do it.'"

"He's my guy, he's my person," she gushed, before revealing the qualities that make their marriage work. "It's communicating, it's listening, it's picking and choosing your battles. It's being flexible, it's all of that." 

"One day at a time, one step at a time," she added. 

Watch Loughlin on When Calls the Heart, airing Sundays at 9 p.m. ET/PT on Hallmark. See more on the actress -- and her adorable daughters -- in the video below.