04/13/2011 at 12:00 PM EDT
admits she loves glamming it up as a judge on American Idol
or for her upcoming album, Love?
But at home with husband Marc Anthony
and their 3-year-old twins
, Max and Emme, Lopez is a zero-makeup kind of mom. "That's when I'm my happiest," she says in this week's exclusive cover story. "Just being able to touch my face and rub my eyes and put my fingers in my hair and not having to worry about messing it up. It's so much better."
From her skincare regimen to her grueling workouts and portion-controlled diet, Lopez says she makes a concerted effort to stay in top form. "The thing is, it's part of my job," says the singer, who ran a triathlon
six months after she gave birth. "I don't want anybody thinking it's easy. It does take time and it's hard work. HDTV wide-screen is nobody's friend!"
Lopez, 41, also has learned valuable beauty tips over the years, and says daughter Emme is starting to prove she's her mother's child. "She is very girly-girl, just like me since I was very little. She loves for me to paint her nails," Lopez says. "She lays out her clothes on the floor like I do with my stylist and she's like, 'This matches very good!' "
And what about son Max? "He wants to paint his nails too. Because for him, it's just paint. He's like, 'I want the blue!'" Lopez says, laughing. "Then Marc is like, 'Why are Max's nails painted?!' But he won't sit still so it's only like two nails."
As for being called a "diva," she says, "I kind of like it. We've kind of owned it now. But I certainly don't like and I've never been a person who has what they call 'diva behavior,' which is something they tried to pin on me for a long time."
For more of Lopez's exclusive interview, in which she sets the record straight on all the rumors, pick up this week's special issue of PEOPLE, on newsstands Friday