Making Sense of Sin: Father Matthew Presents

How have you come to understand sin? We confess every Sunday:
Most merciful God,we confess that we have sinned against thee in thought, word, and deed, by what we have done, and by what we have left undone. We have not loved thee with our whole heart; we have not loved our neighbors as ourselves. We are truly sorry and we humbly repent. For the sake of your Son Jesus Christ, have mercy on us and forgive us; that we may delight in thy will, and walk in your ways, to the glory of your Name. Amen.
What does this _mean_?