Mandy Moore Says Filming Her 'Weird, Special' Indie Film Saved! in 2004 Was Like 'Summer Camp' (Exclusive)

Mandy Moore is taking a walk down memory lane. 

The actress and singer, 40, reminisced about the 20th anniversary of her movie Saved! while talking to PEOPLE about her new campaign with TJ Maxx — and says she still remembers filming like it was yesterday. 

“I'm bombarded with memories of set. We all were staying at the same hotel together while we were shooting, and I just remember all the time we would spend with each other in one another's rooms. Like, ‘Okay, we're all going to Jena's room today.’ Or, ‘Oh, we're all going to Eva's room today, or Mac's room,’ and we made dinners or we ordered food and we just hung out,” she says. 

Moore played Hilary Faye, best friend of main character Mary (Jena Malone) in the film, which follows Mary as she tries to "save" her boyfriend from being gay and ends up pregnant in the process.

Moore and Malone's costars included Macaulay Culkin, Eva Amurri and Mary-Louise Parker. 

“It was like we were all 17, 18 years old, maybe some of us were a little bit older, but it was such a fun summer camp experience,” Moore says. “And we knew that it was a really weird, special, little tiny thing. It wasn't lost on us what we were doing.” 

Moore, whose new “Claim Your And” campaign with TJ Maxx is designed to encourage women to define themselves on their own terms and to embrace all the different parts of their identities, had already released her smash hit "Candy" in 1999 and starred in cult favorite films The Princess Diaries (2001) and A Walk to Remember (2002) prior to the release of Saved!.

Looking back, Moore says she also remembers her early fashion choices — both the good and the bad.  

“I'm sure I'll probably look back years from now and be like, ‘What was I thinking?’ But I think that the fashions of the late '90s, early 2000s were not my cup of tea. Even at the time I was like, ‘I don't like these low rise jeans. These are not for me.’ But I did it! That is not something I'll be revisiting right now,” she says with a laugh. “I know it's popular again. But you live and learn, that's part of being a young person.” 

And, speaking of the 2000s, Moore also recently revealed to PEOPLE what her favorite part of “Candy” actually is. 

"I'm a big fan of the spoken word part," she said. "I love [it] because it makes no sense to me: 'You know who you are. Your love's as sweet as candy. I'll be forever yours. Love always, Mandy.' I remember when I was doing that way back in the day thinking, this is insane. This is so strange. Will this work? Will people understand this?"

Though her sons with husband Taylor Goldsmith, August "Gus," 3, and Oscar "Ozzie," 19 months, haven't heard the hit, Moore says they are familiar with another one of her successful singles. 

"We have our bedtime routine with Gus and it involves reading books and telling stories, which we call 'once upon a times,' and then we sing songs," she said. "We normally sing one song of mine that is from the last album of mine that no one knows, but Gus knows and asks for. But the other day he goes, 'Sing, "I Wanna Be with You." ' And I was like, what? What do you mean? And he's like, 'Sing, "I Wanna Be with You." ' And I was like, 'How do you know that song?' "

Just last month, Moore and Goldsmith announced that they're expecting their third child, a girl, together.

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Posting a photo of her two sons holding hands, the big siblings-to-be each wore a white T-shirt. Gus' said "Big" and Ozzie's read "Middle."

"Sometimes life imitates art," Moore, who played a mom of three on NBC's This Is Us, wrote in her caption. "The third in our own Big Three coming soon. Can’t wait for these boys to have a baby sister. 💓💓💓."