What Inspires Your Characters?

In order to move your plot along, you have to have your character decide to do something. You've created conflict, so there are problems, to build suspense there are more problems. Something has to change, something has to bring the story to its climax.
While it may be tempting to make events beyond your character's control bring about the resounding crescendo of your novel, readers are much more enamored by a story if the struggling protagonist actually does something that makes all the difference. This is where your character needs inspiration. Generally, this is in the form of a catalyst - something new introduced to the story that awakens the lead.  It may be hitting rock bottom as a result of an especially catastrophic event. Just like what inspires alcoholics to go to AA, the situation gets so bad for your character that they are forced to recognize that something has to be done.
Your character may be woken up by something another character does or says at just the right moment - a slap on the face during a wedding by a grandmother who has always been only kind, a statement by a co-worker that makes the character realize that her impression of who she is, is far from how others see her. It may be that a new person or relationship in their life makes your character realize things can't go on the way they have been.
Perhaps it's something subtle like a glace in the mirror at a friend's house or the way a fish struggles on the end of the hook during a camping trip.
Inspiration can come in the form of a long-repressed memory coming to the surface, or a silly poem, or the look on a dog's face.
Your plot, theme, setting, and characters will all guide you toward the best choice for your book. Just make sure your readers feel it as intensely as you do.