the power of the mind

how is it when you are doing so much better your strength wears out and the mind can mess with you? you think you're in control and your mind proves it can overpower itself and tear you down? to try and comprehend this has given me a headache and has twisted my brainwaves. ugh no wonder people go crazy, when all it takes is your own mind. strange things to have happen and try to understand. take my word for it, just let it go and leave it be. for your own state of mind and well being. its not worth getting into. at all