Amanda Seyfried stars in the new coming-of-age comedy “While We’re Young” about a couple in their 40s played by Ben Stiller and Naomi Watts who befriend a couple in their 20s portrayed by Seyfried and Adam Driver. FOX411 spoke with the 29-year-old actress about having that moment when you realize you’re one of the grown-ups in the room. She says she feels Hollywood is actually a “detriment to growing up” for certain people.

FOX411: What was it like to be the resident young-in on the set?
Amanda Seyfried: It was good. Recently, I’ve been so shocked at the idea of being older than people because I feel so young and naïve, depending on the day. But it's fun, I mean, I got to play the young version of me and it's always great when there's no consequences and I can run just around in my bare feet and just kind of feel like I don’t know, just happier, and carefree, and it’s always good to… you always hope that that character rubs off on you.

FOX411: So are you then having those moments already, that shocking realization where you’re like, I am a grown up in the room now?
Seyfried: I have to behave like a grown up. And as hard as it is and as tough as it… as intimidating as that is, I realize it's the only way to be, it’s the only direction. It's the only way your life is going to work, you have to be mature, and you have to make mature decisions and you have to think of other people, and you have to be responsible. And you know what? My life is better for it.

FOX411: Yeah, is part of it Hollywood? Your job?
Seyfried: I actually think it's a detriment to growing up for certain people. Certain actors stay kids forever because they're treated like it. And you just can't stand for that, when people sometimes… people treating you like a kid, you're just going to like kind of stay that way if you're not careful. I'm only speaking from experience, so I realize it's really important to stake your claim in the adult world.

FOX411: Is there pressure in another way in Hollywood, pressure to stay young, pressure to stay on the trendy side of things, do you see that?
Seyfried: I think when I'm working, I want to wear, I’d rather be wearing something that's kind of fashionable, in the moment, but there’s not that much pressure. I don't think too much before I leave the house in terms of like getting dressed… I think also because I live here maybe there's less pressure. There are thousands of industries here in New York.

FOX411: In the film, the 20-somethings get VHS and Vinyl?
Seyfried: It’s because they don’t know it. And they want to preserve it because it's cool, maybe there's a cool factor, maybe it’s just that like it's archaic to these younger people. I mean, I'm 29 and that was my childhood. That was the way things were until I was in my teens. So I don't want to preserve that s--t, it’s not doing me any favors.

FOX411: Is there something you hold onto not because it's ironic, but because you think it's just better?
Seyfried: Book[s]. I will not read books on my iPad because guess what? That can also, the battery can die. The battery dies all the time. I almost bought a flip phone the other day because I was thinking, what if, this battery keep dying so much on my iPhone. Books, books, I have to read books it’s just so simple. You don’t need to plug it in.