Jennifer Lopez has always doubted her singing ability.

The 'On The Floor' hitmaker admits she used to be insecure about her vocal range and it wasn't until she met her ex-husband Marc Anthony - whom she has five-year-old twins Maximilian and Emme with - that she began to realise she was a successful international popstar due to her talent, and not her flawless looks.

Speaking to Britain's Cosmopolitan magazine, she said: ''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, 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. Then I grew, little by little, and realised, wait a minute, this is not a fluke. I'm not a mistake - I work my ass off. And I know what I'm doing.''

The 44-year-old star split with Marc in July 2011 and has been dating choreographer Casper Smart, 26, since October 2011, but she admits her hunky beau has to work for her love.

She explained: ''For me, it's about having a great partner to walk this life with. I have my own high standards for what I want in a partner and how I want to be treated.

''I bring a lot to the table. I'm not talking about the material things but what I have to offer as a person - love and loyalty and all the things that make a good relationship.''