Why learning to deal with disappointment is key to human development.
One of the most important ideas I’ve ever heard is the story of the old king. The king asked to be made an item that would make him sad when he’s happy and happy when he’s sad, so a ring was made which was engraved with the words
“This feeling is fleeting.”
This is important in that, while happy feelings will fade, as will those of disappointment and sadness. No matter what happens to you, no matter when or what it is, the sun will come up tomorrow. While there aren’t second chances, there are next times: times when you can make yourself better and meet the goal you want to achieve. And now you know what is wrong and what you can do better. Nothing is ever accomplished by hanging your head at the first sign of failure. Keep calm and soldier on.