It can become easy to get upset over things that happen in your life, especially if it comes from someone else. People tend to get angry with others over small slights. Many times people will choose to be angered with someone due to a small action that they did. These actions can easily be ignored and you can continue to go along and have a happy day.
When you stop to waste your time on someone else, it is pointless, you are wasting your time on someone who is not crucial to your growth. You don’t gain anything from having conflicts with anyone.