"Competitive golf is played mainly on a five-and-a-half-inch course, the space between your ears." -Bobby Jones
I've heard or read this quote many many times having grown up playing golf. I always thought it was a little cliche, but essentially true given the nature of golf and the huge mental and emotional swings (no pun intended) your game can have in just one round. If you go back through history, the best golfers are the ones that can block out all of that noise, all of the distractions, and just play their game. The level of concentration it takes to not only avoid big mistakes, but quickly recover from a bad misstep here or an errant drive there.