Never.

Oscar Wilde said that if you know what you want to be, then you inevitably become it -- that is your punishment, but if you never know, then you can be anything. There is a truth to that. We are not nouns, we are verbs. I am not a thing -- an actor, a writer -- I am a person who does things -- I write, I act -- and I never know what I am going to do next. I think you can be imprisoned if you think of yourself as a noun.

Stephen Fry