OK, fine, in spite of the general silliness of this thread, I'll bite...
First, knowledge. I want to know what a doctor knows and put it into practice. And I want the sense of power that comes with that knowledge. I love learning. I'm actually looking forward to the intensive coursework of medical school, not just practicing medicine.
Second, personal challenge. I know I'm going to outgrow my current job in a few years. I'm ready for something new that will stretch me in ways I can only imagine. I love the intellectual challenge of differential diagnosis. I love the visuospatial challenges of anatomy, histology, and imaging. I look forward to the challenge of learning physical exam skills and interacting with patients.
Third, fear of regret. I first considered pursuing medicine many years ago but ended up following a different path because I was intimidated by the whole process of medical training and the enormous responsibility of diagnosing and treating patients. Well, I'm older and more mature now, and I'm no longer so intimidated by those things. If I don't go for it now, I will regret it for the rest of my life.
Fourth, greater income and status than I have in my current job. In my current position, I help many people, I have a leadership role and job security, and most of the time I enjoy what I do. Medicine offers all of that and more. But I hasten to add that it will be many, many years before I can break even financially (i.e., pay off the opportunity costs of losing my current job and the debts of medical school), let alone get ahead. Money matters but it truly isn't the only thing motivating me.
