As a man needs change and continuous moving on by mental and physical ways, a novel needs the characters to "live" in the story. If the patterns of "life" doesn't change and stays the same, life will cease to live within the man, woman, or story.
Also depending on the scenario , life can be good, bad, right, wrong, life , or death. So to live your life and the characters live their life in the story, something in their life or the surroundings involved with the characters need to change whether it be good, bad, right, or wrong. With that said, the change decides who lives the chosen life, and how it is to be lived in a physical way or in a novel so that the reader understands the characters way of life, consistency, and acceptance of life.