Currently, my goal is to turn my hobby of painting miniatures into a side business. I find that I don't mind painting miniatures, or sculpting miniatures for pay, because it feeds my creative side.
And since my day job is being a stock boy at a grocery store, that's a side of me that gets rather starved.
As for doing it full time? Only once the hobby hit the point of consistently bringing in enough that I stopped needing the day job.