Self-discipline's apex is always solitude, and solitude's apex is also freedom.
Old Car Says 375:
I am nearing the end of my life, with 28 years of work experience and 20 years at well-known multinational companies. I've traveled to many cities and met many people. Among the self-disciplined people I've encountered, they always have goals each day, people with boundaries and standards in their work, strictly following systems and procedures, with a sense of reverence, doing what they should, with the courage of a tiger, smelling the roses. Self-disciplined people will definitely learn to give up, understand giving up, and willingly forgo the popularity circles that many people are obsessed with. Being alone is always the solitary figure of self-disciplined people. Surrendering to one's inner voice is the frequent monologue of self-disciplined people. Perseverance is the common trait of self-disciplined people.
The taste of loneliness is actually a carnival within the self-disciplined. I've always tried to be self-disciplined, preferring to sit alone in loneliness, because the gifts of self-discipline in work, life, and health far exceed the sacrifices I make to maintain self-discipline.
Self-discipline's peak is always loneliness. Loneliness's peak is also true freedom. I particularly love this sentence

Simple matters, do them carefully and persistently.

Inner strength is far stronger than outward showiness.

Four years and more, I consistently maintain good health, enjoying the joy of solitary exercise.