The thing about performance, even if it's only an illusion, is that it is a celebration of the fact that we do contain within ourselves infinite possibilities.
You don't merely give over your creativity to making a film -- you give over your life! In theatre, by contrast, you live these two rather strange lives simultaneously; you have no option but to confront the mould on last night's washing-up.
Being at the center of a film is a burden one takes on with innocence -- the first time. Thereafter, you take it on with trepidation.