God does not require our thanksgiving for the fulfillment of any need in His heart or emotional sensibilities. He exists as a perfectly self-contained being, as it were, completely and forever fulfilled within His own triune personhood of Father, Son, and Holy Spirit (Acts 17:24-25).
Our Lord rather desires our gratitude and finds great pleasure in it because it originates in the faith whereby we rightly relate to Him. Thanksgiving meets a need in us rather than in God. "The just shall live by faith" declared both the prophet of the Old Testament, and the Apostle of the New (Habbakuk 2:4; Romans 1:17). Thus, we are only truly alive when we trust God, a major component of which involves the thankful heart that reveals we are aware and appreciative of God's faithful heart. This pleases Him because He so greatly desires our well being and best interests. "In this was manifested the love of God toward us, because that God sent His only begotten Son into the world, that we might live through Him" (I John 4:9).
We affirm appreciation to God for the purpose of honoring Him. "Whoso offereth praise glorifieth Me" (Psalm 50:23). We also bless His heart with our offerings of gratitude. "The prayer of the upright is His delight" (Proverbs 15:8). Such attention directed toward our Lord and away from ourselves also graces our own heart with the thanksgiving that, as A.W. Tozer wrote, "sweetens the soul." Gratitude thereby comprises mutual blessing of both the Divine and the human. We do well to keep this much in heart and mind as "out of His infinite riches in Jesus, He giveth and giveth and giveth again," and out of grateful hearts, we thank and thank and thank again.
"It is a good thing to give thanks unto the Lord, and to sing praises unto Thy name, o Most High."