"Do not let the behavior of others destroy your inner peace".
An important lesson I learned is to control the things that can be controlled. There are many factors in our life that influence the way things are. Realizing that many of those things are out of our control, and coming to terms with those results is an essential piece to a happy life.
For example, you can’t control the call a referee makes during a game, which very well could change who wins and who loses. But, what you can control is your effort, your preparation, and attitude. We all should evaluate our own performance and results from the lens that makes the most sense through what we can control.
Similarly, other people’s behavior could affect the way you are feeling, especially if you care about them and their well-being. But, at the end of the day, their behavior and choices are out of your control and should not dictate the way that you feel. Have confidence in yourself, and you will see that you can maintain that inner peace you are so dedicated to achieving.