The way you treat people shows a lot about who you are as a person and how you carry yourself when things do not go according to (your) plan.
Some people tend to exert their negative feelings onto others because they realize they have lost control. Others may choose to look on the bright side of things and take obstacles in life as part of the journey. The way we were raised by our parents and society also comes into play on how we handle ourselves in stressful situations.
Keeping calm and handling things with grace comes with practice. The more we see how things (typically) don’t go according to plan, the less worried we get and understand that it’s just part of the game.