“All discipline for the moment seems not to be joyful, but sorrowful…”
That goes for both parties. Both the Discipliner and Disciplined. It’s not pleasant. Haven’t we ever heard the common refrain from the parent that is raising their hand to bring discipline down upon the seat cushioning of a child, “This hurts me more than it hurts you”? That’s typically more a figurative statement than a literal one (however, the discipline can leave a parents hand stinging as well). For the moment, the discipline is sorrowful. The parent is sorrow their child has done wrong, and the child is sorrowful they got caught. The parent is sorrowful that their instruction was not followed. The parents is sorrowful that their warning(s) were not heeded.
That’s why people don’t want to do it, and why they oftentimes do not do it.
But this is what sin brings about. Where there is no sin/foolishness there is no cause for discipline. Where discipline already exists, there is no need for one to be disciplined. It is only when we are not discipling (following), that we are not personally disciplined, that we need to be disciplined by authority. “For rulers are not a cause of fear for good behavior, but for evil. Do you want to have no fear of authority? Do what is good, and you will have praise from the same; for it is a minister of God to you for good. But if you do what is evil, be afraid; for it does not bear the sword for nothing; for it is a minister of God, an avenger who brings wrath upon the one who practices evil.” (Romans 13:3-4)