In light of what God had done for Israel, David was moved to celebrate His grace, patience, mercy, and consistent love. However, David also had personal experience of these facts about the Lord. In spite of David's affair with Bathsheba, God had shown him mercy and unmerited favor by withholding death from him. After David confessed his sin, the Lord forgave him and demonstrated His love for him.
It is important to note that David, the psalmist of Israel who wrote these beautiful verses, had to face tremendous hardships and great difficulties. However, the testimony of his life was that he looked back upon the compassion and grace that the Lord had shown to His people. As well, he looked forward to the coming of the prophesied Redeemer, who was destined to personify the overabundance of lovingkindness and tender mercies for all His people. 
Our Lord understands intimately how we were formed and how fragile our lives are. Our Lord knows and loves us. As difficulties arise in our lives and we are faced with hardships and trials on all sides, it is important that we adopt the attitude of David in his many psalms of praise and thanksgiving, praising God for all the blessings He bestows upon us.

Dear Heavenly Father, I bless Your holy name, O my soul, for You have pardoned and healed me, forgiven and redeemed me, and crowned me with kindness and compassion. Not only do I trust in You, but I also appreciate Your faithfulness, mercy, love, grace, and patience. In Him, I find all that I have, am, and hope to become, as He gave His life for me, that I might find life in Him. 
In Jesus's name I pray. Amen.