What you have studied and learned in philosophy should not make you harder on other people, only harder on yourself. Immature people use knowledge as a weapon. Wise people use it as a shield—to protect themselves and to protect others.
This is what Ben Franklin meant in his epigram, “Search others for their virtues, thyself for thy vices.” When you look at other people’s behaviors, you should find what’s good in them, what you’re grateful for. When you look at yourself, you should see what can be improved and where you fell short.
The idea of Stoicism is to be realistic and forgiving of your fellow men, but ambitious and aggressive in how you push yourself. Your standards should be so high for your own behavior that you must stretch and stretch to achieve it—if you ever even can. Your standards for other people must be set so that you are pleasantly surprised when they meet them and willing to make due when they don’t.
It is in this balance that you will find growth—and happiness.