Discipline isn't punishment. It's the most self-respecting thing you can do: choosing your own hard instead of being handed one.

The thought behind it

This line works by turning the expected explanation inside out: the thing you were blaming turns out not to be the thing. Quiet Power is unglamorous by design: the version of you it builds is the only receipt you get. Watch what “hard” does here. Change it and the sentence becomes comfortable again, which is how you know it matters.