Many people have worked for me, but the great ones, the really useful ones, are always passionate. Passionate people have enthusiasm. If they want to get to the second floor, they will devise a ladder to get there. Extremely enthusiastic people think about how to get where they want to go and the steps involved. Devising something like a ladder will not occur to those who merely think it would be nice to get to the second floor. I believe that only the people who are so passionate that their only goal is getting to the second floor will come up with a tool like a ladder.
Working without passion is pointless. In the end, human beings are passionate creatures, and we all grow rapidly when we have not just knowledge and skills, but passion as well.
Source : "Shainkagyo (The Business of Being an Employee)"