“Your Self-Confidence and Your Performance,” by prof. Artur Poczwardowski is posted at www.stadion.com/sports-psychology/.
This four-part article explains what self-confidence is, what can happen if you are over-confident or not confident enough, and how to develop, maintain, and in the case of an athlete who lost self-confidence, how to restore it to an optimal level.
The author, Artur Poczwardowski, is a sports psychology consultant. He graduated from Gdansk University (M.Sc. in psychology) and from AWF–University School of Physical Education (M.Sc. in coaching). He competed on a national level (in Poland) in judo. Currently he is a professor at University of Denver, teaching and conducting research in sports psychology.
Read his article about methods of developing and restoring self-confidence, beginning with the first part: