I am talking about temperament. Every single person alive today has a breaking point at which they break and show their other side.
The reason some seem to be this calm and cool guy is that they learn to manage their temperament. They tame it and force it to be the passenger in their life while they remain as the driver.
They control their personalities and keep a watch on their emotion to avoid the other side taking over.
When you as an individual can do this, trust me, you will have a peaceful life.