I spent years as a professional writer and then started to write just for me, initially, wondering if I could pull it off (actually I'd challenged another writer friend of mine - a short-story writer to write a novel - I thought this would be good for him, to stretch himself. And of course, he pulled it off which meant that it was now my turn.) I had a longish short story in process, which I turned into a novel, The Big Crunch, quite a few months after him. Then I spent about a year editing and polishing it up!