a way to channel that which has always worked for me in competitive sports is first you wouldn't be there unless you had the skill.
you know what you're capable of
when you get stressed in a match where you think you're doing poorly, take a deep breath, remember why you even started playing in the first place , for fun
i dont know i would always get stressed then try and remember when i actually was really young i did it for fun and for personal achievement, even if you don't win if you are doing better then you would have last week or even last year that's awesome.
when you're angry just take deep breaths and know you got it because the only time you get upset is when you know you can do better, confidence!
i just blabbered and had no real point here
cheers
