What upsets you is not what happens. What upsets you is your response to what happens. Just as easily as you respond in a negative way, you can easily and naturally respond in a positive, empowering, uplifting way.
The biggest problems are often caused by what you choose to do about the smallest problems. Most of those big, painful problems are so unnecessary. Keep reminding yourself that you are in control of you. You are in control and you can decide exactly how you wish to feel at any point.