How do you stay motivated?

So you've started a new story. It's all fresh and new, and you can't stop thinking about it. Your characters are really coming to life, and you are really beginning to care for them. You're cruising right along and then BAM! You lose interest.

I really don't like it when this happens to me. I'm not exactly sure what sparks this sudden non-desire, but my hard drive is riddled with abandoned stories.

I've found that when it really counts and I have to finish the story, I'll find pictures of what I think the characters look like. I'll either cut them from magazines or find them online. Having a clear idea of who they are, and then having them staring at me is really motivating. Or, if I've based the characters loosely on someone I know, I'll either visit or find out someway (Facebook) how they are doing, thus piquing my interest again. These are odd little quirks - I know - but I'm pretty much a visual person, so having either the storyline, images, or even just the list of characters in my face, helps me focus.

Does this ever happen to you? What makes you move on? What keeps you from abandoning your wip - other than a concrete deadline?

Another new story, but only a partial

I'm off and writing a new partial for my agent. Even though I've written one other middle grade partial, my agent told me to start on a new story while she's shopping the one full MG and the partial MG manuscripts. I guess from now on, since I've written a full in each genre I write, I only need to write partials for her to submit. I'm not sure if all agents work this way, but mine does. And, I have to say that I really like it. I don't have to commit myself (or the time) into completing an entire story. I can write a partial and synopsis and then move on.

The only downside that I see to this arrangement is that perhaps my enthusiasm for the story may wane if I don't keep plugging along. I've got several women's fiction manuscripts that are partially completed because I lost interest. But those cases are different, I think (I hope) because I hadn't written a synopsis and they were written early in my writing career - meaning, I've learned a lot more since then and I'm sure if I went back to those, I'd see the problem I lost interest - no clear story problem.

Either way, I think it's pretty cool that I only have to commit to three-five chapters and write the dreaded synopsis.

How do you write? One full story at a time, or in partials?