They will test your limits and they are capable to make you let out the worst version of yourself, so it is about controlling your emotions and actions, don't let anger get the best of you, I am telling you this as someone who fails lousily at applying this rule, and I do regret it a lot when I calm down (don't worry I don't hurt my kids, it is mostly screaming at them or being too severe when they make mistakes and I am not proud of that)