Not just control not to cry in public but also your anger. Anger can create violence or harm people when you don't know how to control it. Sometimes you can pass it to another person who doesn't do anything for you.
I believe that people who don't know how to deal with their anger can kill their loved ones because of too much emotion. Anger can control your mind, plot things, makes you think too much, or worried too much that makes you hurtful. It whispered to your ears what revenge you will do. It makes you violent, aggressive, and dangerous. Sometimes it makes you out of the character. It gives you the power to do things that are impossible for your character.
So you need to calm down when you're mad before you take an action or make decisions. Don't let your emotions eat you up. So don’t make a decision when it involves emotions.
Great one