Before I started writing short stories, everything I produced was a potential first draft of a novel. I would plough on with it for weeks or months and finally get bored with it. Working on the assumption that if I, the writer, am bored then there isn't much chance of anyone enjoying reading it, I have ditched project after project. MYWYN - http://80kwords80days.blogspot.com/ - has given me a reason to continue. I can't emphasise enough how reassuring and simply companionable it is to rub (virtual) shoulders with other writers and aspiring writers and cheer each other on and up! Through other writers I have come to realise that everyone struggles at times and that the first draft is a useful framework to model the next draft on, but not a perfect, carved in stone work of art. It's ok to get bored with what I'm writing because when the draft is finished it can all be changed. I have also learned not to edit as I go along (or 'Addit' - http://teresa-morgan.blogspot.com/ ) because I get so embroiled that I go round and round in circles and lose sight of what I was meant to be doing - e.g. finishing the darned story!
I have to say, though, that even though I am persevering better than ever before with writing my novel, I get the occasional ache to write a short story and feel the heady satisfaction that creating something complete in the space of a few hours brings.
Maybe I don't have the patience to be a writer of novels - I think I'm a bit of a quick-fix junkie - but we'll see!