Jennifer Lopez says her life has changed since welcoming twins Max and Emme two years ago.

"I can't help but be a different person now that I've had kids. That really does change your whole perspective on life for the better," the singer-actress, 40, tells the May issue of Redbook.

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"I definitely feel like I've grown up," continues Lopez, who next stars in The Back-Up Plan (in theaters April 23) and will release her album, Love, this summer. "So, I guess in a way, parts of me are going to be different, but in general I'm still the same girl from the Bronx who had big dreams."

"I always wanted to be great at what I did -- that's what drove me. If I got rejected, I wouldn't take it personally," Lopez continues. "I was like, Make them a fan and they'll bring you back in for something else.

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Adds Lopez, "A marriage is long, and you've got to like the person as much as you love or lust after them. You've got to be friends first."