Read The 38 Most Common Fiction Writing Mistakes for Free Online Page B

"just happens" to walk by the store on the one afternoon when it's for sale, and it "just happens" to fit her perfectly, and she "just happens" to get there five minutes before Annabelle, who also wanted the dress.
    Readers may not realize why they don't believe your story when you allow this kind of sloppy plot planning to ease the way for you, but they won't like it.
    After your first draft, watch with an eagle eye for coincidences, either ones you might have impatiently allowed in the first write-through just to get on with it, or (even worse) those you simply didn't recognize earlier as outlandishly lucky.
    How do you fix coincidence? First, you excise it. Second, you search for a way by which your character can set out seeking the desired event, person or information. If your character wants something, and works hard to get it, it isn't coincidence anymore.
    Having provided your characters with sufficient background and motivation for their actions, and then by making sure coincidence doesn't rule the day, you'll be well along on the way to better story logic. Things will happen for good reason, and your readers will love you for it.

11. Don't Forget Stimulus and Response
    Story logic goes deeper than providing good background motivation and avoiding coincidence. Even if you're an ace on these matters, your copy still may be flawed in terms of having things happen for no apparent reason. That's because fiction readers may need more than background and good motive for what their characters do in a story.
    Readers will also usually need to see a specific stimulus that causes a given response right here and now.
    The law of stimulus and response dictates that your character must have an immediate, physical cause for what he does. This immediate stimulus cannot be merely a thought inside his head; for readers to believe many transactions, they have to be shown a stimulus to action that is outside of the character—some kind of specific prod that is onstage right now .
    So for every response you desire in a character, you must provide an immediate stimulus. Turning this around, it's equally true that if you start by showing a stimulus, then you can't simply ignore it; you must show a response .
    The law of stimulus and response works at the nitty-gritty level of fiction, line to line, and it also works in melding larger parts of the story. For every cause, an effect. For every effect, a cause. A domino does not fall for no immediate reason; it has to be nudged by the domino next to it.
    Let's consider a bit further.
    The chapter just before this one looked at character background and plot motivation before mentioning stimulus and response because it's important for you clearly to understand the difference. Background, as we have seen, goes to earlier actions affecting the character's life. Motivation has to do with the character's desires and plans, which grow out of that background, as well as out of what's been going on earlier in the story. Stimulus is much more immediate: it's what happens right now , outside the character, to make him do what he's going to do in the next few moments.
    For example, if in your story you want your character Martha to walk into the personnel director's office to seek a job, you need some background to explain why she needs a job; perhaps she comes from a poor family and has no means of support (long-term background) and maybe she just lost some other job, and so needs a new one right away (short-term background). She has made the decision to apply at this company because she just spent her last few dollars to pay her rent (even shorter-term background, combined with motivation).
    Even so, you can't just have Martha sitting there in the office, suddenly get up, and walk into the personnel director's office. In fiction, that won't work; it will seem unreal, incredible. What you have to have is an immediate stimulus to get Martha to get up and walk in now .
    So you write something like:
    The