Dear Jerusha - I'm currently working on my WIP, a thriller/drama which I think is a really good idea and I love the plot. However, I'm struggling to get motivated with it. But after churning out a few short stories this week, I've realised just how much I love writing humorous stuff. It just feels more natural. I have an idea for a chick-lit style novel, but I know this market is declining rapidly. So what do I do? Go with my head and finish the book that I think has a good chance? Or go with my heart and write the stuff I really enjoy? Some friends say there's no point in writing something I'm not enjoying; others say that "write what you want" is a luxury no professional or would-be professional can afford, and I ought to buckle down. The thriller is my first novel, so maybe it is about finding my voice. I did finish it but it really needs a re-write to make it tighter. I read a range of books, from thrillers to horrors and the best chick-lit so that might be why I'm so confused!
Well, I'm not an expert, because I spend more time counting parasitic Antarctic wasps than studying the bookshelves in the Walsall Tesco, but it seems to me that when there's talk of the market for chicklit declining (or any other longstanding subset of a main genre), all that's happened is that a) the really huge new authors are, by definition, writers who've worked out or stumbled on a newer slant on that genre, and b) the overt packaging into a very clearly defined product for a clearly defined market has declined. I don't believe there isn't still a market for women's fiction with a sense of humour and romance of one stripe or another. So although you might want to try to find a way to pitch this novel as something which isn't quite your bog-standard chicklit, I don't see that it's a doomed kind of novel in itself.
But on the main question, it's important that this thriller/drama is your first novel. There's a lot to be said for a first novel being thought of as a prentice piece. It's the way you learn your trade by tackling the problems that your project poses - although no one piece of writing will teach you to tackle writerly problems that it doesn't contain. It's also where you discover your nature as a storyteller, just as we all spend our teens discovering if we're better suited to being a backroom boy such as a film makeup artist or a performer such as a sales rep. That's what's important about "write what you want to write": it's not sheer self-indulgent amateurism (though it may be, and there's nothing wrong with amateurism), it's a real understanding of how creativity works. Your suggestion that you haven't perhaps yet found your voice is absolutely central to this: I think you find out much more about your writerly self - what gets your best writing out of you, what moves/stirs/makes you laugh - if you follow your nose/heart/instincts.It's when you really know your writerly self that your writing really takes off, and it's only writing that has taken off which stands a decent chance of selling.
The first novel Emma ever wrote came out a bit like yours sounds, she says, although I can't judge whether she's right because it's buried in her attic on 5¼" disks. She had these characters, this family history, and because she was a beginner - literally, had written one short story since school - she didn't know what to do to get them moving and doing things so that the history and situation would start working itself out. So, she says, she set up a ridiculous plot about a lost briefcase and some Terribly Important Documents. But she kept having problems because getting the plot moving meant her characters had to do all sorts of things which didn't really make sense. Thank goodness the computer ate the middle third of it, she says; she did go on to re-write that middle third and then finish the novel, but it was broken-backed at that point and never recovered. But the next novel was a big stride better.
So one option is to treat your first novel as the place where you find yourself, and if this thriller/drama keeps running aground because the practical demands of the genre don't float your boat again, then it's not the right project. I'd suggest going with your instincts about what really works, as a piece of your writing - because that's a big, flashing sign towards what you'll end up being able to write best. And if the humorous side of your writerly nature is happy writing shorts, then why not do them at the same time? There are lots of times in the writing (and re-writing, and revising, and editing, and polishing) of a novel when it benefits from going in a drawer. And if your writing-time is shaped like most of ours, then you will sometimes have a small chunk of time sitting, like Rockall, in a sea of Real Life, when it makes much more sense to draft a short story than try to get back up to speed with the novel.
But if you're really yearning to use that humorous voice and take on life on a novel, that's a tougher decision. You're right that if you want to be professional about this you can't just jump ship when things get tricky or dull. Might you have reached the 30k doldrums, just rather later than most of us? Or even the writerly equivalent of the seven-year itch? Not to say that it's an illusion that you've enjoyed writing the humorous stories, obviously. But whether that makes you want to put the novel aside might be as much to do with the novel, as the stories.
So the hardened professionals do have a point: despite what I said further up, the fact that a piece of writing has gone difficult or dreary on you isn't necessarily a flashing sign that it's the wrong project. "Write what you want" often isn't easy, not if it's worth writing. It can be incredibly difficult. Just a different sort of difficult from writing to fit a mould your writing self was never meant to fit. Yes, you have to use craft to tilt what you're doing towards a form that stands a chance of selling. But that's very different from trying to write something you're not built to write, just because it's a kind of thing that sells. For what it's worth, Emma has been passionately involved with the WIP of the moment (both before she was published, and now) and still had days or even weeks when writing it was exactly like pulling teeth. She take craftsmanly pride in the fact that (she hopes) no one except her would know which bits of the novel came easily and which were like pulling teeth. That doesn't meean that a) she shouldn't have been writing it, or b) she's a consummate professional with bills to pay and no airy-farty nonsense cluttering up her sensible head. It means she's a writer.
As well as not yet having found your voice (in the broadest sense), perhaps you also haven't yet developed the writerly instinct that tells you when a project is wrong for you. You may feel as if you've been writing this novel for years, but in terms of the growth of a writer, these are childhood days. Like Emma's mother, who can't tell you if your sauce is thick enough without taking the spoon and stirring, it's one of those things that you don't know you feel, till you feel it. That's another reason for following your heart in these early stages: you don't develop instincts except by listening to their first attempts to steer you, and in the longer professional term those instincts are important for surviving. It's not that this thriller/drama isn't a great idea, and it's not that you don't have a decent toolkit with which to work it. Maybe it's just that, actually, you're not, or not yet, the writer who can do it most justice. That's not to say you never will be: Emma's not the only writer who often needs several goes at a much-loved project before she finds the right way - and the right skills - to do it justice. And, conversely, if the hard-nosed professionals know anything, they know how to recognise which, of all the saleable projects they might tackle, has a space for their heart inside it.
When it comes down to it, you and your kind of writing is a bit like a marriage. Making a marriage work - keeping it going - can be very hard work. You can't easily ignore the usual patterns of life that society is set up to accommodate, or those which it doesn't accommodate easily; or, rather, if you do ignore them you may have to take the social and economic consequences. But if you weren't in love in the first place, why are you bothering to make it work, when it's such hard work? At best the marriage will be an emotionally dead, sterile place. At worst it'll be a waste of two lives. It's probably not worth deciding to develop a writing self, in other words, unless you were passionately involved in the first place.