The Biggest Mistake Writers Make and How to Avoid it at Writer Unboxed has a big connection to my long-term thinking about plot. The article is written by Lisa Cron, whose book, Wired for Story, I happen to be reading.
I am not the only writer who struggles with plot. What I've come to believe is that those of us who find plotting hard do so because we don't know the story we want to write about yet. Our ideas come in the form of scenes or situations. There is no "something that happens to somebody and what it means." Without the basic story that we can describe in a sentence, how can we possibly create a plot? "Wouldn't it be neat if someone woke up and found she could fly?" describes a situation. In order for it to become a story, what happens to that character as a result of the situation and what it means to her life have to be worked out
So we all have to learn how to back up and figure out the story. The horse (story) really needs to go before the cart (writing the story).