Denise Richards didn't need much time to decide she wanted to spend the rest of her life with Aaron Phypers.
The two tied the knot in a surprise wedding in Malibu on Sept. 8, just days after news broke of their engagement. As Richards tells ET, though, she and Phypers knew they were going to marry "for quite some time."
"I didn't know the date... we were trying to figure that out. And then the 8th is a very significant number for him. He says it means infinity, so we just decided, 'You know what, we don't want to wait, and let's just do it,'" Richards exclusively told ET's Nancy O'Dell at the premiere of her new movie, The Toybox, on Friday. "I called [celebrity event planner] Mindy Weiss, and we pulled it together very quickly."
Richards and Phypers had been dating for over a year. Phypers finalized his divorce from Nicollette Sheridan last month, two years after their separation.
Phypers and Richards' wedding came together in "less than 48 hours," but the actress is well aware it wouldn't have been possible without Weiss' help. "If we didn't have Mindy Weiss, we would not have been able to do it. It would've been, like, in our garage probably," she said with a laugh. "She did a beautiful job and it was really sweet. It was very close family and friends, and everyone said that it looked like it had been planned for months."
"[We] wanted to make it about us, and the girls, and Aaron and I, and our love," Richards added, noting that she and Phypers are "very spontaneous." "We're very happy."
Weiss wasn't the only one working hard to make Richards' surprise wedding day perfect. Designer Mark Zunino previously told ET that Richards gave him a call to create her gown just 24 hours before saying "I do." The pair decided that stunning runway sample was the way to go, and the actress walked down the aisle in a romper with a silk organza overskirt.
"I was so glad that it was a romper because we left on Aaron's motorcycle, so I didn't want to have this long dress and have to hike it up. And it's my second wedding, so I didn't want the big ballgown," she explained. "We loved it. He did an amazing job. I loved what he did."
Richards admitted that she didn't have to do too much work letting friends and family know that she and Phypers secretly decided to become husband and wife. "They actually called us after, because they heard it," she confessed. Richards and Phypers are now focused on married life -- and her new movie, The Toybox.
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'The ToyBox' Trailer: Denise Richards and Mischa Barton Fight for Their Lives (Exclusive)
"Movies like this definitely do scare me," she added, revealing that her oldest daughter, 14-year-old Sam, whom she shares with ex Charlie Sheen, is a big fan. "My oldest daughter is definitely into the horror genre, so she was very excited that I was doing it."
"My middle daughter [13-year-old Lola] does not want to see it. She doesn't want to be scared," she added. Richards said her third daughter, 7-year-old Eloise, is "too young to see it." "This is a family vacay that goes sideways quickly," Richards explained.
See more on the actress and her family in the video below.