Some call it positive thinking, mind over matter, and holistic medicine. Let me address the positive first. I have witnessed a serious car accident victim proclaim that thy will survive when their chances were almost nil. I have worked with cancer patients who refused to give up only to have their cancer disappear. There have been many times where some clients on their death bed have held on for days waiting for a loved one.
Successful people refer to a positive state of mind when dealing with obstacles.
Sadly, I've seen this also. Negative thinking could be the person who refuses to admit that the chest pain he is experiencing could be his heart. Or the person who refuses to believe that rectal bleeding could be a sign of cancer. Some call this kind of thinking denial. Maybe it is.