Michael Jordan's words speak to something a lot of people quietly wrestle with long before they ever attempt anything difficult, the question of whether they genuinely believe they are capable of achieving it in the first place. "You must expect great things of yourself before you can do them," he said, a line that has been repeated so consistently over the years, across dozens of independent collections of his quotes, that it has become one of his most widely recognised statements on ambition and self-belief.