1) Even as a child I identified as an artist. My mother often recounts a story about me drawing in church when i was perhaps 3 years old and a woman asked me if I was going to be an artist when I grew up. I turned to her without hesitation or arrogance and told her that I already was an artist. I wonder now what my concept of artist was at that time. Clearly it had something to do with making pictures and not much with being an adult. So I always identified with the title and the name artist. Quitting didn't fit with this sort of identification because it has little to do with external factors and everything to do with a deeply internalized belief in who I am. However I have a constant struggle to figure out what sort of an artist I am. I am shifting gears all the time, feeling like I should constantly be somewhere else practicing in a different way. I have never been convinced that I was any particular type of artist: painter, writer, illustrator, animator, actor, musician, all things I've dabbled with. So my commitment to a medium and a craft was always flimsy but not to the larger project of living a creative life. I get very depressed when I am not making something. The question is never whether to make, but what and how to make it.
2) I have thought about this question for a week, and I still don't have a good answer. All my thoughts sound either grandiose or self effacing. I simply don't have an answer.