Isla Fisher has admitted she had to fake confidence when she arrived on the set of The Great Gatsby.
She said: "You know that phrase, fake it till you make it? That's what I did.
"I hid my fears and pretended that I belonged on set with Leonardo DiCaprio - not in the catering truck, helping myself to a sandwich."
Mum-of-two Isla explained how she gained weight for her role as Myrtle in the movie.
"I was breastfeeding, so I had a little flesh of my own, I am proud to admit, but I also gained 10lb just by following my natural instincts - cupcakes," she said.
She also talked about finding similarities with her character: "Myrtle has so many big dreams, so I thought back to the dreams I had. I have been so fortunate - I never imagined that I would be here, working in Hollywood."
Isla, who is married to Sacha Baron Cohen, said she had found fellow Australians working in the movie industry very welcoming.
"The Australians in Hollywood are so supportive and inclusive - there's an Australian ball and Australian barbecues," she explained.
"There is a laid-back sensibility and a sense that we all feel very lucky to be employed in Hollywood."