Steven Pressfied, the author of The Legend of Bagger Vance, Gate of Fire and many other fine books has written about this. While his article is directed at writers, I think it is every bit as applicable to those of us who study martial arts.
An excerpt is below. The full article may be read here.
By Steven Pressfield | Published: December 12, 2012
The question is, “What’s the main difference between a pro and an amateur?”
My answer: depth of commitment.
I’ve always wanted to meditate. But my depth of commitment is unbelievably shallow. I can’t count my breaths past twenty. And pain in the knees? At the first twinge I’m up and outa there. It’s pathetic. I’m ashamed of myself. I’m an amateur. I will never succeed on my meditation cushion, and I don’t deserve to.
I lack depth of commitment.
One way to measure depth of commitment is to ask yourself of any calling, “How much adversity am I willing to endure to pursue it?”
Can you stand being broke? Can you live in a garret? Are you willing to work through pain—emotional, psychological, spiritual? Can you weather doubt, fear, despair?
The artist or entrepreneur must be like the hero of a movie. He has to be the protagonist of his own life, meaning be willing to pursue his objective (rescue his daughter from kidnappers, save the earth from vampires, kill Osama bin Laden) to the ends of the earth and then catch a ride on a rocket and keep on pursuing.