This is important, Gallwey suggests, because there is a constant inner conversation going on in all of us. One part of us tries to focus “on the game.” While it tries to play tennis or speak English, the other part is always giving instructions – “do this, don’t do that” – and evaluating, or criticizing, what we’re trying to do. When the second voice is louder, and we begin to worry about how well we’re doing, we don’t play or speak as well as we could.
via An English lesson from a tennis coach — Successful English.