It must be the byword of all activities within the unit. It does not come naturally. The leader must work at it. Standards must be set, articulated and enforced. No infraction is too small.
Ignorance is no excuse for the leader.
We didn't really mean what we said when we said you must do it. Whether he observes the infraction or not, if it occurs in his unit and he does not correct it, he is undermining the worth of his unit. The leader must work at discipline. He must observe with a critical eye all that is going on around him. He must make corrections.