I wanted to help those who were suffering. That's what doctors are supposed to do. A serious interest in anatomy and biology are also probably good ideas, and something that I'd expect my doctor to have.
If you're questioning whether or not to become a doctor, perhaps trying to weigh the benefits of eight years of school, hard school and residency, versus lots of money in the future... then you shouldn't become a doctor.
No one should go into any career for any reason beyond its what they like to do and are interested in. I love geology and music. I got degrees in both. Did I go into either expecting to get rich? No. Because I enjoy doing them? Yes.
Of course, if it's something that you can't make a living at, say, "I love pottery," then yeah, you need to pick a career that you like enough to do that you'll be able to make enough money to live