When I was very young playing baseball, I dreamed of being a professional baseball player, but gave up that dream when I couldn't even make the high school team :). I majored in accounting in college, largely because an 8th grade test had indicated I should be an accountant and a senior level Bookkeeping class was the only one I ever took and got straight A's with little effort.
An interesting twist in the Army (accounting/finance not open when I enlisted after flunking college) sent me in another direction. I attempted to enter accounting/finance after my initial training as a clerk typist (it was now open), but was told that my typing speed was too fast and they would be wasting my skills ... go figure!
Fortunately, after spending 5 years as a clerk typist and admin specialist, I was able to switch to another previously identified aptitude ... computer programming. There I discovered my true love and expertise ... still loving it and even more since I got into web development. I'm quite confident that I would have been truly bored with accounting if I had succeeded in college (it was the other stuff, not accounting, that threw me a curve).
Like Andrew, I also considered professional ministry, but did not get as far as seminary. Now I have the best of both worlds ... making a living doing what I love and serving the Lord as a lay missionary doing something else I love.