“A professor gave a balloon to every student. Each of them had to inflate it, write their name on it, and throw it into the hallway. The professor then mixed all the balloons and the students were given 5 minutes to find their own balloon. Despite a hectic search, no one found their balloon. At that point, the professor told the students to take the first balloon that they found and hand it to the person whose name was written on it. Within 5 minutes, everyone had their own balloon.
The professor said to his students, “These balloons are like happiness. We will never find it if everyone is just looking for their own… But, if we also care about other people’s happiness, we’ll find ours too..””