The aim of this paper is to point out the importance of motivation in sport achievement and to describe the psychological aspect of motivation, as one of the most important psychological factors for success. Motivation theories give definitions of terms and previous knowledge of different authors, and the second part of this paper gives the most commonly used techniques: Goal settings, cognitive restructuring, and imagination, and how to apply them. When it comes to motivation in sports, some important concepts and some of the most important interventions for motivating athletes presented in this paper can be analyzed in the psychological training of athletes. Special attention given to the importance and the role of trainers in the process of motivating athletes emphasizes psychology as a key factor in sport achievement.