Man came from a hunting and gathering society where it was crucial to be an athlete to survive.  Running, jumping, judgment, hand-eye coordination and touch were all elements that contributed to our survival.  We first ran our game down.  Then we threw rocks.  Later we shot arrows.  Common sense allows you to trace our progress up to today.
          The point I am trying to make is that we would not feel the need to keep honing our skills if it were not for natural forces that we don't completely understand.  Watch a kitten for about 30 seconds and you will witness an animal honing his skills to survive.  He's practicing all the time.  Even with a big ole bowl of cat food sitting 3 feet from him.
          When we were hunting and gathering it was a consuming battle to eat but it was not all that was on our mind.  Procreation of the species was also very important.  In order to procreate we had to find a mate.  One of those human females were by far the most attractive object to vent this frustration on.  The problem was all the other males wanted them too!  Competition was born.  The one who could shoot the arrows the straightest got the gal.
          Understanding competition makes it easier to deal with.  Why does it make you mad to lose?  How important is it to win?  Answer these questions and deal with them and you can become a better pool player.  Too bad they changed the prize to trophies.
          The Yak Factor is merely a form of self-hypnosis.  Don't get nervous you are already practicing The Yak factor  every day.  You blink your eyes don't you?  Do you remember every blink or for that matter any of them?  Do you drive for miles and then sort of wake up and wonder how you got this far without remembering part of the drive.  Did you ever have a round of pool where you finish and are astonished at how good you did but cant remember quite what you did to accomplish such perfect play?
          You can turn the ability to focus on and off through simple self-hypnosis.  Its nothing supernatural its just control of something you do all the time.  In a few hours you can harness the power and get better at it every day.