Events don’t disturb people; the way they think about events does. Even death is not frightening by itself. But our view of death, that it is something we should be afraid of, frightens us. So when we are frustrated, angry or unhappy, let’s hold ourselves responsible for these emotions because they are the result of our judgments. No one else is responsible for them. When you blame others for your negative feelings, you are being ignorant. When you blame yourself for your negative feelings, you are making progress. You are being wise when you stop blaming yourself or others.
From Epictetus’ Enchiridion