Virginia Woolfe:

"So long as you write what you wish to write, that is all that matters, and whether it matters for ages or only for hours, nobody can say. But to sacrifice a hair of the head of your vision, a shade of its colour, in deference to some Headmaster with a silver pot in his hand or to some professor with a measuring-rod up his sleeve, is the most abject treachery."

My version:

"Write what you want, regardless of whether anyone other than you loves it. If you sell out, whether it's for the tangible rewards of commerce or the psychological strokes of Good job, you will turn into Kafka's monster."

That's not to say you can't have a job -- even a job that pays well -- only that you can't sell your soul. No matter what.