2 Chronicles 34:27 Because thine heart was tender, and didst humble thyself before God, when thou heardst his words against this place, and against the inhabitants thereof, and humbled thyself before me, and didst rend thy clothes, and weep before me, I have even heard thee also, saith the Lord.
Josiah was a godly man and a great king. It is not that he was so good, but it was that his heart was tender, he was humble, and he repented. Humility and penitence made him good, for God heard his prayers. It is like the tax-collector who went to his house justified rather than the other. God responds to those who are weak and needy, and in their humility they recognize their need for God and His mercy.
When we are humble and powerless we turn to the Lord for help and He is always there. It is when we are proud, and doing okay, and thinking we can handle life on our own that we get into trouble. It is when we are humble, helpless and trusting that we live well and succeed. Daily repentance keeps us both humble and successful.