Becoming an Artist

At what point does one become an artist? Is it when one recognizes it in oneself that grants that validation? Is it when a piece of art has been sold? Complimented? Maybe it's the day the accepted letter arrives in the mail to that great art school. Could it be the completion of art school...as "pomp and stance" rings through your ears, one can finally have some validity to their passion? Whatever it is, I still struggle with calling myself artist when people ask me what I do. Too bad we don't have good old Clement Greenberg around, then I could just call him up and ask for his opinion!