I was reading Hugh Macleod's post on How To Be Creative which currently has 13 items on the list and was struck by some of what he wrote on point number 7, don't quit your day job, where he explains the The Sex & Cash theory

7. Keep your day job.

I’m not just saying that for the usual reason i.e. because I think your idea will fail. I’m saying it because to suddenly quit one’s job in a big ol' creative drama-queen moment is always, always, always in direct conflict with what I call "The Sex & Cash Theory".

THE SEX & CASH THEORY: "The creative person basically has two kinds of jobs: One is the sexy, creative kind. Second is the kind that pays the bills. Sometimes the task in hand covers both bases, but not often. This tense duality will always play center stage. It will never be transcended."
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A good example is Phil, a NY photographer friend of mine. He does really wild stuff for the indie magazines- it pays nothing, but it allows him to build his portfolio. Then he'll go off and shoot some catalogues for a while. Nothing too exciting, but it pays the bills.
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Or geeks. You spend you weekdays writing code for a faceless corporation ("Cash"), then you spend your evening and weekends writing anarchic, weird computer games to amuse your techie friends with ("Sex")
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I'm thinking about the young writer who has to wait tables to pay the bills, in spite of her writing appearing in all the cool and hip magazines.... who dreams of one day of not having her life divided so harshly. Well, over time the 'harshly' bit might go away, but not the 'divided'.

"This tense duality will always play center stage. It will never be transcended." As soon as you accept this, I mean really accept this, for some reason your career starts moving ahead faster. I don't know why this happens. It's the people who refuse to cleave their lives this way- who just want to start Day One by quitting their current crappy day job and moving straight on over to best-selling author... Well, they never make it.

That blog post sums up a lot of my thinking recently. Designing the classes in System.Xml is a decent day job but I only really light up in front of a computer when I'm fixing bugs or adding features in RSS Bandit. One pays the bills, the other allows me to express myself without artificial limitation in my medium of choice.

If you have time you should read Hugh's entire list, its actually quite insightful.