What you think becomes true. If you have negative thoughts constantly going through your head then negative things will happen to you and your body. If you think things are getting better then you will start to notice things improving in your life.
Your mind has a powerful subconscious and unless you control your subconscious then your subconscious will control you. Change your thoughts through repetition and focus. Create a powerful mind by planting seeds in your mind and letting them grow.