Psalm 51: 14
Give me back the joy of your salvation, and a willing spirit sustain in me.
Commentary:
The Psalmist is asking God to give him back the joy of his salvation because he lost God’s favor due to his poor choice to commit adultery and murder. The second part of the verse is very important to understanding how he could restore his relationship with God and experience the joy of his salvation. By praying for a willing heart, the Psalmist is asking God to make him ready and prepared to receive the joy of salvation. Being ready and prepared to experience the joy of salvation is about changing our character. By saying I am willing it means I desire to change character and become a person that is worthy to experience the joy of God’s salvation so mean what you say and say what you mean.
Saint Joseph Men of Integrity Group 
Another rendition is “uphold me with a willing spirit” indicating the psalmist realizes that it is by God’s grace that he may have a desire to be restored to intimate relationship with God.
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Previous comment continued: …and it will be only through God’s grace that he will sustain that relationship.
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