anxiety makes me think  

I like how you describe your mind during the day of exam - unstoppable. But I believe that preparation is very needful and important. Our mind can have assimilate a certain information in a certain span of time and it needs some time to do so. Therefore, it is necessary to read ahead of time and study even just little by little. In time, your mind will form the habit and it will be easier for you to study well. Cramming is not a good habit.

My mind never stops. It;s like someone duct taped the on switch or something. Even if I don't feel stressed my mind is always going about this and that. I think it is the chemicals in the brain that are all outta whack due to anxiety itself.

My mind works better under pressure, too. I would cram for tests the morning of the exams, and then ace them. If we had two weeks to write a report, I would try to start it right away. Then, I would go back and read what I had written, and it would be awful. If I waited until a day or two before the report was due, however, I would write extremely well. This tactic works well for some people, but other people need a lot of preparation time to learn the information, become comfortable and confident that they really do know it, and then they can write about it or take the test and do well.

Yes true, brain thinks and changes based on situations, whereas heart is one, which feels and acts same and will hurts when we do wrong.