Everyone saw David as a boy who only played with sheep and knew nothing about fighting in battle.  David saw himself differently because He had favor with God.  Had God never positioned him as a shepherd he would have never killed a lion and a bear and would have never been prepared to slay a giant.

Seeing Yourself

David was looked down on because of his position as a shepherd over sheep, but he saw his position as something else.  So never allow the way people see you, the way you see yourself.