The Judo Kid :

A 10-year-old boy decided to study judo despite the fact that he had lost his left arm in a devastating car accident. The boy began lessons with an old Japanese judo master. The boy was doing well, so he couldn't understand why, after three months of training the master had taught him only one move.
"Sensei," the boy finally said, "Shouldn't I be learning more moves?"
"This is the only move you know, but this is the only move you'll ever need to know,"the sensei replied.
Not quite understanding, but believing in his teacher, the boy kept training. Several months later, the sensei took the boy to his first tournament.
Surprising himself, the boy easily won his first two matches.
The third match proved to be more difficult, but after some time, his opponent became impatient and charged; the boy deftly used his only move to win the match.
Still amazed by his success, the boy was now in the finals. This time, his opponent was bigger and stronger. Concerned that the boy might get hurt, the referee called a time-out.
He was about to stop the match when the sensei intervened. "No," the sensei insisted, "Let him continue."