The heart is fragile and can easily become disordered by many things. The prayer set my heart in order is what I see in Psalm 6. David longs for deliverance; what he is going through keeps him awake at night. Into this situation, God orders his heart so he can say,
The Lord has heard my plea; the Lord accepts my prayer. (Ps 6:9)
The Lord puts to rest the question how long? (v. 3). Perhaps the situtation changed, perhaps it did not. But his heart changed, reordered. Perhaps that is the greatest work of God in any situation.
Lord, set my heart in order.