I thought that when I want to achieve a goal, that my fear was from doubt that I could reach it successfully. I hadn't thought of the possibility that I wanted to reach the goal and that simultaneously part of me didn't want to reach it. Suppose I smoke and I decide I want to quit. Whether it is smoking or some other personal habit change, it will be some time before I can retrain myself. I can expect to want a cigarette or watch the news again today or eat licorice or whatever.
I have always framed the matter mentally as a matter of persistence and reliability: can I, will I stick to my resolve or not? But the actual wanting, the desire has been a lower ranked question. I have not actually felt much draw to continue the habit I want to get rid of. I imagine that I might feel two pulls: no cigarette and a smoke. I might feel them simultaneously and both pulls might be rather strong. That pull toward yes and the pull toward no can be bothersome; the stronger they are, more bothersome.
Some explanations of motivational interviewing explain situations where people really do want to commit an action and really do want to not commit it as the same time. The explanations state that such contradictory urges create anxiety, sometimes of rather severe levels. Some sorts of uncertainty will not be tolerated by the mind and one way to stop the push/pull contradiction is to fail, to give in, have a smoke. But that way also makes me a failure. I have been a failure and I don't like. By the way, some literature says that the more I fail, the more dislike I will develop for being a failure and the more strength I will have to succeed.
A motivational interview helps me reaffirm my interest in the new path, the new habit, the new me. It helps me recite what I know and what I feel about my plan to develop a new way of being. The more I picture myself conducting myself in the new way, the more I reaffirm the advantages of the new habit and recall the disadvantages of the former way, the more motivation I will have to continue on the new path. I may even get to the point where a tug toward a cigarette is immediately converted into a reminder to congratulate myself on the progress I am making.