Where's Your Vision?

I read this story at the end of the ebook What's Your Target by Roy Palmer.

A young boy travelled across Japan to the school of a famous martial artist. When he arrived at the dojo (school) he was given an audience by the Sensei (teacher). 

 "What do you wish from me?" the master asked. 

"I wish to be your student and become the finest karate student in the land," the boy replied. "How long must I study?" 

"Ten years at least," the master answered.

"Ten years is a long time," said the boy. "What if I studied twice as hard as all your other students?" 

"Twenty years," replied the master. 

"Twenty years! What if I practice day and night with all my effort?" 

"Thirty years," was the master's reply. 

"How is it that each time I say I will work harder, you tell me that it will take longer?" the boy asked. 

"The answer is clear. When one eye is fixed upon your destination, there is only one eye left with which to find the way."