Here's something that you might want to try when you're angry at or frustrated with a person or people in general. Try saying to yourself, "I wish you happiness." when you look at the person or people. It sounds corny, but it reminds you that everyone wants and deserves happiness. This is a practice that I learned at a Tibetan Buddhist meditation retreat in Nepal many years ago. Sometimes I walk down the street and think, "I wish you happiness" about everyone I see. It never fails to improve my mood!