Why did I choose my major?

When I was a junior high school student, I did not know much about how many subjects/majors there were and what they did. I just studied very hard for entering a great senior high school day by day like any other third-grade classmates. One day, one of my classmates told me that there was a college boards , and he desired to get the entrance. I thought it was a good chance to get an experience before high schools' association tests, so we had the test together. Unfortunately, he did not pass the test, but I did. When I got the entrance, I was not happy at the beginning. However, I was tired to study for those high schools' association tests from morning to night day after day, so I decide to go to the college. And I was assigned to the Department of Mechanical Engineering by the scores. That's the reason why I "choose" my major.