Certainly as an actor, half of your work is not going to end up on the screen anyway, because in the editorial process, they need to cut to the other actor in the scene. Very often, your best work ends up on the cutting room floor, because it just doesn't work with the overall narrative drive of the story.
I love directing more than anything in the world, and I love being in the editing room. I love cutting. When I'm shooting, I cut it in my head anyway. That's not to say that it always turns out that way, but you have a sense when you're composing a sequence or a scene how you want it to look anyway.