Don't worry. Just review and not just before the tests, but read everyday. If you study at the last moments, you might start wondering and worrying whether you have forgotten something. Enter the exam room with a clear purpose. Do not think of anything else. Pray, and start the exam.
Do not think of it as a quiz, exam, test, whatever. Think of it as just a list of questions with no real outcome one way or the other. Just a 'let's see what you know'. Or imagine it is something passed to you by a trusted friend who wants to know
I am assuming that it is academic exams. The best way to deal with the fear is preparation, study well ahead of time, perhaps with a study buddy. Try to anticipate the type of questions, and practice doing those. On the day of the exam, make sure you are well rested and well fed. Do no spend your time worrying, as that is counterproductive. If you have studied your best, prepared well, you should be able to come in calm and centered.
I always think of exams as "brain teasers". I think of them as a challenge that I want to attempt.
If this is seriously impeding your life you should consult your doctor for some chemical help. There is no shame in this, and it shouldn't impair your ability to do exams.
Whether you mean a scholastic or medical exam what has always worked for me is a sense of humor, relaxing and taking a deep breath and knowing it's not the end of the world if the outcome isn't exactly what you might be hoping for :-) You'll be amazed at how helpful it is to not take exams too seriously emotionally. It's almost all about attitude and the fear will go away with a positive attitude adjustment. :-)
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