In his book, Remember Who You Are, William H. Willimon of Duke University says that he recalls one thing his mother always told him whenever he left the house to go on a date during his high school days. As he left the house, she would stand at the front door and call after him, "Will, don't forget who you are."
We know what Mom Willimon meant, don't we? She didn't think Will was in danger of forgetting his name and street address. But she knew that, alone on a date, or in the midst of some party, or while joined by friends, he might forget who he was. She knew that sometimes all of us are tempted to answer to some alien name and to be who we are not. "Don't forget who you are," was the maternal benediction.
The disciples that morning as they fished without success were called from the shore by one who was calling them back to who they were. They were his children. They were his with a mission to do. And that mission would not and could not be successful without his guidance and presence.