JoJo has felt "jealous" of Selena Gomez at different points in her career

In her new memoir, 'Over the Influence', JoJo explains: "She couldn't go anywhere without security flanking her and fans mobbing her at every corner.

"It just seemed like there was no sense of freedom for her to explore the world and be wherever and whoever she wanted to be. I imagined that must be suffocating. It made me grateful for the relative anonymity I had whenever I walked down the street."

JoJo released her debut single, 'Leave (Get Out)', back in 2004, and the singer recently revealed that she wrote her memoir in an effort to "make sense" of her music career.

The pop star - whose real name is Joanna Levesque - told Access Hollywood: "This year is 20 years since I started in the music industry.

"I put out my first single at 13, and with that big milestone coming up, I wanted to start to make sense of what the hell has been happening in my life."

JoJo battled depression and anxiety for years, and she's now keen to share her story with her fans.

She said: "I spent so much time being so confused and struggling with depression and anxiety and just really feeling so lost and alone for a lot of my life - mostly in my teens and 20s.

"I wanted to start putting it on paper and seeing if, first of all, I could understand myself and my life a little bit more, and if there might be things that I could share with other people - particularly younger people who might be interested in the music industry or want to get involved, and not deal with some of the things that dealt with professionally and personally."