I play pretty well but, i suck at pressure situations 21-20 for example i choke and lose 21-23 and what kind of mentality should i keep through the game so, how can i train my mental strength?
Be confident with your own game. You tend to be mistakes-prone if you lose confidence and become uncomfortable with every single shots. Practice practice practice
What are you thinking when the score is 20-all? If it's things like "I must not make a mistake", then you could be suffering from negative thinking. Your focus is on mistakes and/or losing, so that's what happens. Whilst I agree with cliffordgooi that confidence is important, repeating the situation may only re-inforce the negative feeling. When things are close, I remind myself that the next point is just like all the others. I remind myself that I've played ok up to now & there's a good chance that will continue. I fancy my chances of winning this one. If my partner or I are serving, I think things like "one more good serve". If we're receiving, I think about a good net kill. In other words, I use 'glass half-full' statements rather than 'glass half-empty'. You may find it enables you to think more about winning and that you tend to win a little more often. Hope that helps. Good luck and let us know what happens.