Achieving complex and difficult goals requires focus, long-term diligence and effort (see Goal pursuit). Success in any field requires forgoing excuses and justifications for poor performance or lack of adequate planning; in short, success requires emotional maturity. The measure of belief that people have in their ability to achieve a personal goal also affects that achievement.
Goal-setting theory was formulated based on empirical research and has been called one of the most important theories in organizational psychology. Edwin A. Locke and Gary P. Latham, the fathers of goal-setting theory, provided a comprehensive review of the core findings of the theory in 2002. In summary, Locke and Latham found that specific, difficult goals lead to higher performance than either easy goals or instructions to "do your best", as long as feedback about progress is provided, the person is committed to the goal, and the person has the ability and knowledge to perform the task.