Hilary Duff reveals what her 'How I Met Your Father' character has in common with Lizzie McGuire

Hilary Duff's lead character on the new How I Met Your Mother spinoff, How I Met Your Father, wasn't too difficult for her to figure out. She'd pretty much been there before.

"She's like, OK, I know I haven't got it all figured out, but I'm gonna keep going," Duff tells Yahoo Entertainment. "She doesn't give up on love and she has this wonderful zest for a, like, thinking something's gonna happen for her. And, and just having that kind of like whimsical outlook, that things will work out, you know, and... she's like dorky and kind of clunky. And I play that great. I think sometimes, you know, from lots of practice with Lizzie McGuire...."

Duff originally played the character in a popular Disney Channel show, which originally aired between 2001 and 2004, when she was a teenager. She said speaking to life in your 20s and 30s is "fun."

"Obviously I'm, I'm sitting in a very different... stage in life than Sophie is," says Duff, who's married and has three young children. "I have a lot more responsibility. But it's fun for me because, you know, I, I became a mom at 24, so my life has just taken many different turns and I've, I've worked for such a long time. And I do have a more stable grounded kind of well, grounded for me... and Sophie doesn't have any of that yet."

While the sitcom stays close to the original — friendships, romantic relationships and laughs — there are some differences. The show exists in the same world as that of the original characters, and there are plans for Easter eggs throughout, but they aren't the same characters.

Another big difference is that the future version of the protagonist, in this case Duff's Sophie, is seen at the beginning of each episode. (Before, the audience saw the future kids of the dad.) Producers turned to a familiar face to play the part of future Sophie: Kim Cattrall.

Isaac Aptaker, who's an executive producer and writer of the new show, says that was a decision made early on.

"And then when we sat down with Hilary to talk about, like, what is our dream version of future? We all landed on Kim Cattrall and thought, like, there's no chance. Like... that's the wish list, and then you get someone else. But, like, lo and behold, she was really excited by the idea," he says. "She got on a Zoom, and we kind of talked her through what it would be. And she said, yes."

Whenever the Sex and the City alum was on set, others found reasons to be there.

"The whole cast came in that day, even though they had nothing to film, just to geek out," he says. "And like, she just crushed it."

— Produced by Jen Kucsak and edited by Jimmie Rhee