You are what you repeatedly do. Excellence then, is not an act but a habit.
Becoming a great band director or an accomplished performer is not an accident. If you require your students to play with their best sound possible at all times, it will become a habit. If you make yourself play with great groove all the time, it will become a habit.
At the same time, if you allow yourself to clip a note to take a breath, it will become a habit. If you allow your band to play heavier when playing fortissimo, it will become habit.
Excellence is indeed a habit. Are your habits today promoting excellence?