"There's nothing as huge as giving birth to another human being and having to be responsible for another life," Lopez tells InStyle, for its September, 15th-Anniversary issue. "There's you before kids, and there's you after kids – and they're not the same you."
The singer-actress, who celebrated turning 40 with a blowout bash in July, says her outlook on all aspects of life – from her music to relationships and business ventures – has shifted gears.
"[Parenthood] totally changes your perspective on everything," says Lopez. "You don't come first anymore. There's somebody else you care more about than yourself."
For the active entrepreneur, that means cutting down on work and stepping down from the "hamster wheel," a previous lifestyle that was all about deadlines – a whirl in which she "felt like I couldn't say no."
"I'm at a point in my life when I just don't feel the need to put out anything unless I totally, absolutely feel it says what I want to say," Lopez says about her music career. She has, however, received inspiration from her twins – especially Max, whose first few steps inspired the proud mom to write a song.
Marital Ups and DownsWhen it comes to marriage, Lopez, who's been wed to Marc Anthony for five years, admits she's "still figuring it out as I go along," and she's had her share of "hard experiences and a lot of ups and downs and a lot of mistakes."
One way she's figuring it all out is by reading books about relationships. "It's the never-ending question – what is the key to love?"
As for what she's gleaned, "I believe that in life you learn through experience," she says. "I'm old enough to know now that relationships take work. That's it's not an easy thing."