Calvin

“How long are you going to wait before you demand the best for yourself and in no instance bypass the discriminations of reason? You have been given the principles that you ought to endorse, and you have endorsed them. What kind of teacher, then, are you still waiting for in order to refer your self-improvement to him? You are no longer a boy, but a full-grown man. If you are careless and lazy now and keep putting things off and always deferring the day after which you will attend to yourself, you will not notice that you are making no progress, but you will live and die as someone quite ordinary.
From now on, then, resolve to live as a grown-up who is making progress, and make whatever you think best a law that you never set aside. And whenever you encounter anything that is difficult or pleasurable, or highly or lowly regarded, remember that the contest is now: you are at the Olympic Games, you cannot wait any longer, and that your progress is wrecked or preserved by a single day and a single event. That is how Socrates fulfilled himself by attending to nothing except reason in everything he encountered. And you, although you are not yet a Socrates, should live as someone who at least wants to be a Socrates.”
― Epictetus (From Manual 51)

“Knowing others is intelligence;
knowing yourself is true wisdom.
Mastering others is strength;
mastering yourself is true power.”
― Lao Tzu, Tao Te Ching

“Be more concerned with your character than your reputation, because your character is what you really are, while your reputation is merely what others think you are.”
― John Wooden

“Character cannot be developed in ease and quiet. Only through experience of trial and suffering can the soul be strengthened, vision cleared, ambition inspired, and success achieved.”
― Helen Keller