I think one of the battles of a christian is to come to understand that they will never be completely freed from sin until they are delivered from their flesh. Also, when we sin, It can be a natural reaction to be angry against ourself and tend to hate ourself, but paul cheers us back up by showing that it happens even to people like him. Another good new is jesus knows that too, and forgives us all while understanding what we go trough on our daily basis. The bible says he even has been tempted in every things himself, although he did not sin.