Q: "Where do you find the motivation?"
A: Motivation comes from a number of places, and depends on the situation. If, as I suspect, we are talking about the motivation to write, and to continue writing, my motivation for that comes from a couple of places.
Firstly: Trying something new a.k.a. Experimenting.
This was a project of sorts that I started, that I now want to see through to its completion - no matter how many years that may take! I give myself a lot of grief sometimes, due to my personal high standards. I had started out doing this just as a means to test myself, to see what I was capable of. I surprised myself, and now wish to see how far I can take it. Will I end up turning all of the drafts I have typed into full novel-length manuscripts? I don't know. What I do know is that as long as I am enjoying it, I will keep doing it!
That brings me to my second motivation: Enjoyment
So many people spend their lives doing things that they feel they have to do, in order to afford to do the things that they like to do. I have to say I have done that myself. Spent hours working hard, just to pay the bills.
Then I discovered that writing was something cheap and cheerful, yet something which really appealed to me. I found it fun! I had discovered a method of "seeing the world" in a way I never had before. I had to research and used Google Earth to explore the areas where my characters live, where they travel, what they do. It really opened my eyes and costs next to nothing! What keeps me coming back to work on my books is the adventure of actually telling a story, creating characters and their backgrounds, lives, motivations and reactions. I love starting with an idea for a person, a scenario or a place, and then building it up until it's almost real to me. I also hope that others will get enjoyment out of reading the story I have created. Of course, when I've worked so hard on a creation like that, I really don't want to leave it alone. I want to perfect it - that is my high standards coming into play again!
Mostly, I think of my writing like an art-form. I'm only going to get better if I practise! I happen to enjoy practising my art, and really - if you love doing something, why stop?