A person does not always know when their judgement is impaired until something happens that makes it obvious. I was walking down the stairs while looking at some papers one time. I stepped out thinking that I was at the bottom of the stairs, but I was not. I spent two weeks laid up due to the injury to my foot. I was very angry with myself for allowing a distraction to impair my judgement. I learned from the experience that I should not read while walking down the stairs! Had someone tried to point that out to me, I would not have believed it. I thought that I knew what I was doing. Most people are the same way. They trust their own judgement until there is a circumstance where it becomes blatantly obvious that there is a problem.