“But you, take courage! Do not let your hands be weak, for your work shall be rewarded.”
As soon as Asa heard these words, the prophecy of Azariah the son of Oded, he took courage and put away the detestable idols from all the land of Judah and Benjamin and from the cities that he had taken in the hill country of Ephraim, and he repaired the altar of the Lord that was in front of the vestibule of the house of the Lord.
God never forgets our efforts. We see here that even kings get discouraged when they don't see tangible results from their righteous choices; but God, in his mercy, sometimes gives us a prophet's encouragement to keep on going.
“But you, take Courage!”
Asa's response is also important to note as well. After hearing the encouragement, he took courage, and began doing even more for God's kingdom. It is up to us, to take that encouragement, and continue doing God's work.
Dear Christian, let us be strong, take courage, and continue fighting the good fight of faith, laying hold on eternal life. (1 Timothy 6:12)