07/22/2009 AT 11:40 AM EDT
It sounds like the fake belly bump Jennifer Lopez
is wearing for her new movie The Back-Up Plan
is giving her some ideas.
The singer-actress admits that she and her husband Marc Anthony would like to give their 18-month-old twins Emme and Max a sibling or two. "I would love to have more kids," the actress tells Extra
. "I don't know if we will. I don't know if that's in the cards for us – but we'll see."
Lopez, who turns 40 on Friday, also opens up about the joys of watching her twins grow up. "They're more than walking now ... They're starting to talk," she says. "I put Max to bed yesterday ... and I said, 'I love you baby. I'll see you tomorrow.' And he was like, 'I love you.' "
Speaking of love, Lopez can't say enough about the positive effects of
motherhood. "You just mature so quickly in such a deep way and you think life is short and you have to just go for things. You can't be afraid to try or do you best ... just do it and that's the example I want to set for my children as well. It's like you can do anything. The only thing that ever holds us back is fear ... It's a useless emotion."