Nothing in this world can take the place of persistence. Talent will not: nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not: the world is full of educated derelicts. Persistence and determination alone are omnipotent.
Movie acting, I later realized, reminds me of contract bridge. Each requires the same concentration, intense short-term memory, and obliviousness to everything else until the last trump is called - or whatever it is they do.