Psalm 31:7 I will be glad and rejoice in thy mercy: for thou hast considered my trouble; thou hast known my soul in adversity,
David wills, makes a conscious choice, to be glad and rejoice in the mercy of the Lord. Even in the midst of trouble and adversity afflicting his mind, will, and emotions he can still choose to be happy. He can do so on the basis of his faith in the mercy of God. He believes God’s character and he knows that God acts according to His basic character of mercy. God is good, kind, and merciful. His mercies are new every morning. And if that is true, he can be glad.
No matter the outward circumstances and inward fears, the Lord is still there and He is always full of mercy. His steadfast love never fails. He considers, sees, and cares about our troubles, and brings comfort and help. And He knows the feelings and fears of being in adversity, and does something about it. Why? Because He is full of mercy, kindness, and love, and not because we are good. How can we know? He has revealed His love and shown His mercy in the Gospel of Christ. We believe it. We receive it. We enjoy it.