The core of your character is character’s ability to CARE ABOUT SOMETHING. To feel implicitly or explicitly that something is important.
Give your character something that looms important to him or her.
Plunge your character into a situation that challenges the part of him that cares, or threatens the thing he feels is important.
Give a character so compulsive a desire to make a given change that she can’t let it be. Then you have the basis for a story.