One experiments is one that was arranged to show the effects of mental practice in sinking basketballs from the free throw line. Three test groups of students were scored on their ability before the practice started. Group A was told to begin physical practice for 20 minutes per day for 30 days. Group B engaged in no practice of any kind for the same 30 days. Group C practiced mentally for 20 minutes with no physical action. They were instructed to imagine they were throwing at the basket. If they felt themselves missing too many baskets, they were told to correct their errors mentally. At the conclusion of the 30-day test period, the three groups were compared again. Group A improved 24 percent through physical practice; Group B showed no improvement; while Group C, which engaged in mental practice only, improved 23 percent! The mind has tremendous power if you understand that you must release it through your imagination. But above all, you must believe you are capable of doing so. Believing in yourself is one of the keys to improvement.