v 12 Restore to me the joy of your salvation,
and make me willing to obey you.
Here is a Psalm you know well! It is full of tears of repentance by David after his affair with Bathsheba. His deep desire is to get back into a joyful relationship with God and experience a heart-change that will carry him forward in obeying Him. These are the two principal elements of the comfort that we most desire and that Jesus offers to those who mourn over their sin.
The first is JOY in a restored relationship. When we sin we may feel distraught and distant from God, but as we repent and God comforts us, then joy in knowing God and walking with Him is restored. This is comfort that touches us at the deepest point in our being. It puts holy laughter in our souls and enables us to walk upright amongst our fellow Christians. It shouts from the rooftop of our lives that we have been forgiven and restored as children of God. Hunched shoulders straighten up and furrowed brows are smoothed over in the joy of a restored relationship.
The second is a renewed willingness to be obedient to God. Not the grudging obedience of a slave but the glad obedience of a child who wants more than anything else to please the Father. This is a heart-change obedience that results from the comfort God offers as a consequence of genuine repentance and mourning for sin.