Motivation is the heart and soul of any character's action or inaction. Without motivation, a character has no need to move, to act or react--coerce, ridicule, praise, lie--and so if our characters lack strong motivations, chances are we won't have much of a story. No one will want to do anything; their need won't be strong enough to get them up off the couch and out the door. There will be no impetus for the story to be told.
Characters want, they yearn, often desperately so, and this motivation rises in direct conflict with an opposing desire. Ultimately there is a climax.
This is the classic architecture of a story: conflict, climax and resolution. Character one has a motivation, character two has an opposing motivation, there is rising conflict-- followed by a climax and resolution.Paraphrased from On Writing Short Stories
Edited by Tom Bailey