Demi Lovato found it challenging to complete her book because she didn't use a ghost writer.

The 21-year-old singer struggled to find the time to write her tome, Staying Strong: 365 Days A Year, which is comprised of inspirational quotes and ideals Demi uses everyday in her life to reach her goals and stop her from relapsing into drug use, bulimia and self-harming, problems she has beaten.

"[The hardest part was] finding the time to sit down and write. A lot of people don't really write their own books [they have ghost writers], which is probably something that anybody who's not a natural author really needs," she said.

Ultimately though, the pressure to get the book to the publishers on time inspired Demi: "You have a deadline, and it needs to be finished!"

Demi - who checked into rehab to be treated for her various problems in 2010 - is grateful her own painful life experiences have helped so many of her troubled fans and she believes they share a special relationship because they help each other. "Now I have probably the best relationship between any artist and their fans, because I have no secrets," the X Factor judge said.