"An amateur lets the negative opinion of other unman him. He takes external criticism to heart, allowing it to trump his own belief in himself and his work. Resistance loves this.
Can you stand another Tiger Woods story? With four holes to go on the final day of the 2001 Masters (which Tiger went on to win, completing the all-four-majors-at-one-time slam), some chucklehead in the gallery snapped a camera shutter at the top of Tiger's backswing. Incredibly, Tiger was able to pull up in the mid-swing and back off the shot. But that wasn't the amazing part. After looking daggers at the malefactor, Tiger recomposed himself, stepped back to the ball, and striped it 310 down the middle.
That's a professional. It is tough-mindedness at a level most of us can't comprehend, let alone emulate.
Tiger didn't react, he acted.
Tiger didn't take it personally.
Tiger didn't use the moment as an excuse to fail."
Steven Pressfield, The War of Art