Like the classic “Christian Liberty” concept where rules can create freedom, in a more generalized sense, discipline enables freedom of choice in one’s life. Discipline is the wisdom to choose someone else’s will over your own.
Imagine that a newborn person, whether physically newborn or spiritually, starts in a field with a circular fence one foot wide. He has to start by accepting “easy” rules, such as “Thou shalt not kill.” Should he come to a crisis necessitating a choice about whether to kill, the consequences are rather obvious, and the choice is usually easy. Once he learns to make the correct choice in easy affairs, he expands his fence by allocating some room to decide. He also must have placed some trust in the rule-giver to decide to obey in the choice, which enables the rule-giver to bestow further options to the obeyer.
The act of choosing is quite powerful. By making any conscious choice, one learns to influence his surroundings. By making the specific choice to obey (the “right” choice in the given moral context), one increases the size of their “safe” surroundings in which they are free to express their own will in their choices, and he builds the relationship of trust with the rule-giver.
The choice itself is also powerful, with a direct and an indirect effect. The direct effect is the immediate expansion of the fence, or the allocation of free space allowing self-expression through the exertion of willpower in the “lesser” choices – the same choices that were great crises in the past. The indirect effect is the enablement of future expansion of the fence, since the trust-building with the rule-giver enables the rule-giver to progressively increase the difficulty — and hence the wisdom gained — of the crises in one’s life.
As an example of one who achieved ultimate discipline, remember Christ in the garden. He wanted the “cup removed from Him,” but chose to perform the Father’s will over His own, and drank from it anyway. That final choice was the consummation of His disciplinary development as a human, and His wisdom demonstrated the ultimate expression of choice in the enablement of transcendence of death itself — ultimate freedom.