Our society loves sports, and (for better or worse) this love of sports means there is a need for psychologists to help those involved in athletics.
Besides psychology, it is also concerned with disciplines such as biomechanics, physiology, and kinesiology.
Sport Psychology addresses the interactions between psychology and sport performance, including the psychological aspects of optimal athletic performance, the psychological care and well-being of athletes, coaches, and sport organizations, and the connection between physical and psychological functioning.
Based on this definition, sports psychologists can participate in various activities, mostly focused on working to understand what motivates athletes and how athletes can improve their performance. These activities can range from counseling athletes who might have anxiety issues that hamper their performance to instructing athletes (individually or in groups) on methods of mental conditioning (e.g., visualization, concentration, and relaxation) to helping athletes deal with injuries.
To put all of this in another way, a sport psychologist is working from the perspective that success in sports relies on both the body and mind. To add one other important point, sports psychologists are often found working with elite athletes—Olympians and professionals. However, sports psychologists can be found working with athletes at all levels as well as with coaches and sports administrators.