Cameron Diaz said she felt "debilitated" by fear waiting for the world to react to her book.

Diaz released "The Body Book: Feed, Move, Understand and Love Your Amazing Body" in 2013. She admitted she was scared to receive negative feedback to her personal book.

"Right before the book came out, I was on my back for a week. My back went out. I couldn't breathe," the actress said at an event for Pearl xChange, according to People.

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"I've never had that kind of thing where I was just literally debilitated. I realized I was just so scared that I was going to put this thing into the world and everybody's going to see me, and what if they don't like me? What if they think I'm crazy or I'm stupid? I was like, 'Oh God, this is so painful,'" she shared.

Although Diaz is used to being criticized (and praised) for her work in movies, the book was the first time the world would be reacting to her and not one of her characters.

"It was revealing about who I was. Movies are like totally fake. It’s not me at all. It is, but they’re characters. This book was all me. There was no hiding. I was so open and so raw," she said.