Lively, 24, said she gets negative thoughts before stepping out at a big event and uses the confident attitudes of Monroe to tackle her anxieties, reported The Telegraph.
"I have insecurities like any girl. I used to be really shy and not confident. I hated being tall. Walking the red carpet is so scary, so I pretend to be Marilyn Monroe - someone who owned their sexuality and projected this incredible aura of self-confidence," she said.
The actress said she feels she has to show off her fashion credentials in real life too.
"There's a lot of pressure to constantly find the best designer outfits. As a teenager, my mum was constantly after me to dress better. She encouraged me to dress up and discover my own style," Lively added.