This is one of the most strategic of Writer's Mantras. Tom Clancy says that fiction differs from reality in that fiction must make sense.
And the sensible thing for a protagonist in most stories is to walk away, and avoid the heartbreak of being torn between Miss Right and Miss Baxter, and avoid getting shot at by villains, and avoid crying when Ole Yeller dies.
So, what keeps your protagonist in the game? Don't tell me, tell yourself and remind yourself as you're writing your story.
For example, let's suppose you're protagonist is Dagney Taggart and she wants to make her family's railroad business a success. That's easy enough. Just make the trains run on time. And if you write a story of trains running on time delivering goods safely and efficiently where they're needed and keeping customers satisfied, nobody will be interested.
To make things interesting, you add conflict. In the case of Taggart Transportation, two problems arise. On the one hand, Dagney can't get high quality metal for rails and bridges. On the other hand, gubmint regs are making it impossible for her to do business (but if you grease the right palms, you can make these problems go away). To add insult to injury all your best people are disappearing.
The motivation to keep her family business intact and profitable pulls Dagney along through the twists and turns of the plot. Along the way she discovers a mystery and starts putting together clues of a general strike being waged by the makers against the takers. Happily, she doesn't have to sit through any long sermons by John Galt, so she remains engaged in pursuing her goal.
(If you don't know what I'm alluding to, find out who's John Galt.)
Most people aren't interested in reading long political diatribes. If you don't believe me, have you read the Unabomber's Manifesto? Or Earth in the Balance?
Many more people will read a story. We all face trouble in our lives. Some have more trouble. Others have less trouble. But everyone has some trouble. We can identify with someone else having trouble and trying to work through it. So, we keep reading. Will Dagney Taggart find out why all the greatest minds of America have gone missing? Will she escape the parasites who infest her life? Will she make the trains run on time? We want to know, and to find out we'll keep on reading despite the polemics along the way.
The novel I'm alluding to is fairly heavy-handed propaganda. It is more pornography than truth. But this mantra is not about telling the truth, but of laying out the architecture of a story. So, look at your current writing project and answer:
- Who is my protagonist?
- What is her story-goal?
- What stands in her way?
Does it make sense for someone, and in particular a person like your protagonist, to pursue such a goal?
How about the obstacle? Does it seem daunting? It should be.
In motivation theory a person will be unmotivated by a trivial task. As the task becomes more difficult the motivation rises. For me more difficult problems are more interesting. But if the task becomes ridiculously impossible, people naturally give up and become unmotivated again. In your life, you'll be most engaged in the problems that are near the upper-limits of your capabilities. Try to live there if you can.
When you're writing, you want to show your protagonist going against an obstacle that is seemingly impossible. The more impossible the better. You want the reader thinking, "Gosh, if that ever happened to me, I'd just curl up and die." And then you've got to use your cleverness as a writer to devise a way for your protagonist to NOT curl up and die, but overcome!
Avoid the dreaded deus ex machina when you do.