18 stars honest about their insecurities —
"The biggest insecurity I had was my singing. Even though I had sold 70 million records, there was this feeling like, I'm not good at this. And while I was married to Marc (Anthony), he helped me get over it. He kept telling me, 'You're the only one holding yourself back from reaching your full potential as a singer. You have to let go'...I was always so insecure and just kind of going along. Then I grew, little by little, and realized, wait a minute, this is not a fluke. I'm not a mistake -- I work my a** off," Jennifer Lopez has told Cosmo.