If your concentration is getting bad, take up bass fishing. It will really improve your ability to focus. If you aren't ready when that fish hits, you can't set the hook. Lee Trevino
I think is very beneficial to relax yourself so that when you are doing it you are not staggering for lines and your concentration is not on what I am going to say - but the scene itself, the character that you are talking to. Dabney Coleman
Being an actor is the loneliest thing in the world. You are all alone with your concentration and imagination, and that's all you have. James Dean
You can't keep your mind on fighting when you're thinking about a woman. You can't keep your concentration. You feel like sleeping all the time. Muhammad Ali