This seems simple and it is but the hard part is when the person doesn't realize the amount of energy they are using to stay the same. Think about those who stay in their addictions. They use extreme amounts of energy to stay how they are. They have to worry about going to jail, their next fix, their loved ones no longer wanting to be around them, and on and on, yet they stay the same. It seems that it would be easier to give up the drugs and addiction so that things would be easier, less energy. So as we work with helping others and more importantly ourselves we must first realize that change is necessary.
So, how does this apply to our characters? Remember, change is resisted by people and that includes our characters. They are not going to up and change just for the fun of it. They need something that will push them to the point that it takes more energy to stay the same than it does to change. We as writers must understand our characters limits, their breaking points that send them too far and the point that pushes them to change.