The American Idol judge was asked during an appearance on The Tonight Show with Jay Leno on Monday (February 13) if she'd had any mentors as a young musician who helped her as she helps the Idol contestants.
Lopez replied: "I had a lot of mentors. Puffy aka Diddy now. When I first met him and was making my first album he gave me a lot of insight into the music business, he'd been in the music business a long time; he helped me a lot."
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As for what advice had particularly resonated with her, she said: "He did say something to me which was pretty funny. I had recorded a song for my first album and played it for him and said, 'What do you think?'
"He said, 'I hate it, it's not good, it's not a hit'. I was like, 'Well, I love it!' Standing up for my music and myself. He goes, 'Good, you can listen to it in your living room!'"
Lopez added: "It stood with me because he's right. When you're an artist it's not just about it touching or moving you, it's about everybody relating to it as well, what will touch everybody. I really learned that from him, even though he was kind of tough with how he delivered the message!"
As for what happened with the song, she laughed: "It was on my first album! Momma's the boss!"
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Lopez - who previously dated Diddy - released debut album On The 6 in 1999. It featured singles including 'If You Had My Love' and 'Waiting For Tonight'.
During her appearance on the show, the star also spoke about the current season of American Idol, which saw one contestant taken to hospital last week after fainting and another throwing up while rehearsing.
A preview trailer of this week's episodes shows another girl collapsing in front of the judges during her audition.
Lopez said: "Hollywood Week was so brutal. I don't know what it was. They were just tired, the pressure, something. I wound up giving them a speech saying, 'You guys, this has to be fun too! This is a great opportunity and we're rooting for you, we're pushing for you guys, you don't have to be nervous when you get up there'."
American Idol airs Wednesdays and Thursdays at 8/7c on Fox.
Watch Jennifer Lopez talking to Jay Leno below: