Fear of change.
I'll be graduating from community collage in a few weeks, so I can say first hand that change is downright scary. You're life's been going along all normal when suddenly you see a turn up ahead and realize anything at all could be on the other side. Yikes!
A lot of story characters yearn for change, for adventure. They're desperate to know what's around the next bend. It's easy to see why those people make for great heroes. You don't have to prod them at all. They're raring to go. Just point them at the plot and stand back! (Taran the Assistant Pig Keeper, in Lloyd Alexander's Prydain Chronicles is one such character.) But there are plenty of protagonists who don't like change at all.
One of my favorites is Muggles from Carol Kendall's The Gammage Cup. Muggles rarely ventures an opinion because she hates to make waves. All she wants is for everyone around her to be safe and content, and as the story progresses, we see that she's willing to go to great lengths -even face banishment!- in order to protect her quiet little village.
People who wait for problems to come to them can be wonderfully interesting heroes. The stakes have to be high to push them into heroism, but once those quiet, unassuming character decide to act, you know they mean busyness.