The only path by which another person can upset you is through your own thought.
Once the subconscious mind accepts an idea, it begins to execute it.
You are like a captain navigating a ship... You must give the right orders, thoughts and images to your subconscious which controls and governs all your experiences.
Specialize in your particular field and try to know more about it than anyone else.
The truth is you can acquire any quality you want by acting as though you already have it.
You can develop the right mental attitude when you realize that nothing external can upset you or hurt you without your mental consent.