Discipline is not what you think
It was my first time hunting. I lay quietly, in the shadow of a small berm, overlooking a field with an abundance of deer scat. The deer knew it was hunting season, so I expected to see nothing and leave empty handed. I dozed in the quiet calm of the sun, lilting in and out of consciousness, patient and waiting. I was shocked when a large buck leaped over the berm almost directly over my head, trotted, and came to a stop less than 10 yards away. It did not see me and had no idea I was there. I raised my rifle and brought the broad side of the deer into my sight. The rules stipulated 8-points or more, so I started counting the antlers. The buck had a large set of antlers, clearly more than eight, but my brain, my intellect, intervened and told me, "Keep counting, count again, just make sure." In that moment, the deer turned, saw me, and bolted away.
Our tradition is strict. One doesn't speak during class and one does not sit on the mat casually. We immediately stop and pay attention when the instructor speaks. We address each other as "Sir" and "Maam", our clothes are clean and well maintained, and our shoes are polished. When a student is instructed to do something by a senior, there are only three acceptable responses, "Os", "Yes Sir", and "Yes Ma'am". To outsiders, this behavior appears subservient at best and cultish at worst. But there is nothing subservient about this behavior.
We are training away self-judgement and doubt. We are teaching ourselves to act instantly and without question. This is quite difficult. The human intellect is powerful and has served us well. Human intellect was honed over generations to build pyramids, bridges, computers, and spacecraft. But there are times when we must act without hesitation and move at the speed of muscle. When the barrel of the rifle is pointed at the deer there is no place for intellect. A command emerges from the void and the body responds without question, judgement, or doubt.
We call this discipline. At the beginning discipline is instilled from the outside. A teacher, parent, or drill sergeant gives the command and you obey. Through reinforcement and repetition the mind learns that protest is futile. As a child your mother tells you "Fold the laundry!" and there are tears and resistance. As an adult the command "Fold the laundry" comes from within and the laundry is folded.
Moving through life doing - not thinking - is incredibly efficient. Through discipline we learn to contain our intellect, and unleash its power on problems and challenges where it is well matched. Otherwise our being is trained to maneuver and act with resolve and commitment, and once the action is complete we move on. There is no self-doubt. Anxiety evaporates. Our actions blend and harmonize with the world around us.
There are many who have come through the door of the dōjō, then turned and left because they were told to cut their hair or their nails. The discipline, they thought, was subjugating them and squelching their individuality and freedom. But to trade the ego for a life of harmony... that is a deal worth making.