What is the word/phrase to mean something that just happens once? For example,
I have often been told/expected to do this and not to do that. I become aimless and gradually lose the idea of who I am. I ask myself "What is the point?" If life is just once thing, why can't I live my life in my own way, the way I think is right and suitable to me? If I cannot, I would rather live a shorter life.