Mark digs into some of the key reasons why people struggle to accurately assess their own lives and conditions. It can work two ways.
1) you can not see your error in the way you live because you can not self assess properly. Time is spent justifying rather than examining.
2) you may down play yourself and not see yourself the way God sees you.
Both of the above hinder us in our walk and hinder is in developing into the man or woman of God that you are called to be.