"Remember, the amateur works until he can get it right. The professional works until he can't get it wrong."
Advice given to Julie Andrews, as a young actress, and she passes it along to us. It is sage advice and can be verified by observation when we see professionals performing. And it goes deeper to understand it.
The professional has three primary tools; knowledge, iteration, and attention. He learns his role from the inside out. Yes, he learns his lines; yes, he knows his blocking; yes, he knows the context of the piece; through repetition he can do it without even thinking about it.
Then, as with any professional, he pays attention to what he is doing, while he is doing it. This is what allows him to perform without a flaw. Should a flaw occur by another, it is what allows him to make adjustments to cover it.
Attention to costume, make-up and props. Attention to the moods and attitudes of his fellows in the cast. Attention to the activities prior to his entrance. Attention to the stage as he enters. Attention to those on stage with him. Attention. albeit peripheral, to the audience and their reactions. His aim is to be "on top of it." To do it, to pay attention to doing it but without thinking about it.
And when it's over, complete relaxation.
"All the world's a stage" and so this can be said of any professional be he an attorney, a doctor, an engineer, an artist or an artisan, a tradesman, and even an actor.
