I don't intend to answer this question, really - because everyone knows that you can't explain exactly HOW that character popped into your head, and you can't really say that he started talking to you about where he wanted to go and who he wanted to meet...
someone said once that to write is to have a socially acceptable form of schizophrenia. I quite agree with this statement! It's incredible how people imagine such complex worlds and get it down on paper where the rest of us can partake of the wondrous new creation.
I was working yesterday (why is it that I always get the best ideas when I'm at work??) and an old story idea that I'd had a while ago popped back into my head. I scribbled it down so that I wouldn't forget it a second time and continued working, thinking through some of the details of the story.
J.K. Rowling said she was getting on a train when Harry Potter just stepped into her head, "fully formed." Sharon Creech describes her writing process as fishing - she "reels in" story ideas and if she doesn't like them, she'll throw them back. Imagination is a wonderful thing and I am astonished, at times, how well people develop it and how people quell it.
One of my favorite activities when riding in the car is to imagine someone flying alongside the road - if I have my iPod or discman (yes, I still have one, it still works!) I'll set action to music and there will be a chase scene, a tragic death scene, or a happy scene...I was making up a story in my head one day while listening to the Lion, The Witch, & the Wardrobe soundtrack, and my sister said, "Agh, I'm so bored! There's nothing to do!" I turned to her and said, "Well, just make up a story in your head, it'll be like watching a movie!" She said, "I don't do that." "Ever?" My eyebrows rose to the top of my head. "No." I was aghast. "HOW DO YOU LIVE??????????????" She just looked at me and rolled her eyes. My sister is a very talented person, but apparently, she does not have any imagination.
I just want to say that...even if you don't think you're a great writer, develop your imagination - and if you want to write, what's stopping you? You'll only get better with more writing (as my husband tells me). Let the story ideas pop into your brain and sizzle for a while, see where they lead! You never know...you might end up with a great career as a writer later on!
Here are some people who had other jobs before they started writing books:
Andrew Clements - He wrote such award-winning books as "Frindle" and "The School Story" after a career as a teacher.
James Gurney - He has written and illustrated several LOVELY books about the incredible world of Dinotopia (which you should read - the illustrations are all in oil and are, in one word, gorgeous). Before he wrote books, he worked for National Geographic as an artist.
Garth Nix (yes, that's his real name) was a part-time soldier, book seller/representative, publicist and editor before penning the brilliant Abhorsen trilogy.