Book excerpt from: Planning for Success by Devin Bull.

A person's "Success Mechanism" is actually triggered or activated by goals. For example if a business person has set a goal to enroll one new client each week, his or her commitment to achieving that goal will tend to make him or her work harder, or go the "extra mile" in an effort to meet that commitment. To the contrary, if that person had no specific goal in mind and the end of the week were approaching, they probably would not pull out all the stops like the goal setter would. Goal setters tend to have a very clear picture of what they are trying to achieve and that in itself is a source of motivation.