The `Red Riding Hood` actress - who has starred in a whole variety of films, from musical `Mamma Mia!` to high school movie `Mean Girls` to playing a lesbian in `Chloe` - says it`s important to appear in lots of different genres as then audiences will believe in your character more.
She said: "I`m an actor. I`m not a socialite. I`m playing a character, I`m playing versions of myself. For me it`s important to be a chameleon.
"I like challenging people`s perceptions. That`s the trick. It`s like a game."
Amanda also revealed how there would never be a `Mamma Mia!` sequel, even though she really enjoyed filming the ABBA-inspired film, which also starred Meryl Streep, Colin Firth, Pierce Brosnan and Amanda`s ex, Dominic Cooper.
She told Britain`s Marie Claire magazine: "It was the best experience ever but a sequel is never going to happen. Like, what would they do? What would they write about? How would they get all the actors back?"