I have a big tournament coming up this week, my big problem is that my mental game gets thrown off very easily and i get very nervious under pressure. when i get nervious my arm is as stiff as a board. my entire mindset gets thrown off. when i am under pressure it takes me all my might to pocket a ball and half the time i will mess easy shots which i will shoot in with ease while practicing. i am not a bad player by any means, i can break and run racks quite consistantly but i just need some advice as to what to think about or what to do when i get nervous because that is when my game goes in the gutter, any advice will help, thanks