You've got this great character, right? She's spunky, a recent law school graduate, and she loves her Friday night writing engagements. Her only hope in life? That she'll meet the man of her dreams (preferrably, a firefighter), and live happily ever after.
Cool, interesting character. Now what? She has to grow, right?
Growth, in its most realistic state, is something that happens over fairly long periods of time. We have to experience life, react to it, process it, and then learn from it. Someone doesn't go from spoiled schoolgirl to serious, intentional scholar overnight. That's where the writer steps in. Our job is to tell the most compelling moments in a character's life. Compelling moments that build up to growth (whether positive or negative).
Sounds easy, right? Not particularly. We're suddenly called to be psychologists, in a way. We draw up characters so rich that they must behave as real people might when facing a similar situation. That means that we're required to analyze behaviors, motivations, and even thought processes.
It's not easy, but it's what we do. At least it's fun, right?