You can be invincible, if you enter into no contest in which it is not in your power to conquer.
EpictetusNo man is free who is not master of himself... Is freedom anything else than the power of living as we choose?
EpictetusYou ought to choose both physician and friend, not the most agreeable, but the most useful.
EpictetusWhat is a good person? One who achieves tranquillity by having formed the habit of asking on every occasion, "what is the right thing to do now?"
EpictetusNeither the victories of the Olympic Games nor those achieved in battles make the man happy. The only victories that make him happy are those achieved against himself. Temptations and tests are combats. You have beaten one, two, many times; still fight. If you defeat at last you will be happy your entire life, as if you have always defeated.
Epictetus