The only tool we have as artists is selectivity. If you're a painter, you select the color, the lines, how severe they should be. As an actor you develop how angry you should be. You select how angry you should be. You listen to the other actor and then you react. In film, sometimes the other actor isn't even there. You have to play the scene. What I do is I call on my experience on the stage. I play the scene and I hope that I reach a certain level of integrity because that's what I learned on the stage.