Concentration and playing at the highest level

I am not sure what the secret is to keeping your sole focus on the music but it is an essential skill to have as an artist. My big band can sound professional, I mean, one of the best at times. At other times, it can sound like symphonic musicians warming up . . . on jazz. Being able to focus for prolonged periods of time is a skill that is nurtured over time, I think. Part of that skill is letting go of, or forgetting about, your mistakes immediately, and keeping your mind in the present. I heard a golf coach say that you have to "bury" the last shot; it's dead, gone and in the past. Whatever the analogy or Jedi mind trick, you must be able to focus on the music at hand and block out other stimuli to play at the highest level.