God made everything for man. Man, however, who is “the only creature on earth that God has willed for its own sake” (GS 24,3), was created in order to be blessed. This happens when he knows, loves, and serves God and lives in gratitude toward his Creator. 
Gratitude is love that has been acknowledged. Someone who is grateful turns freely to the giver of the good and enters into a new, deeper relationship with him. God wishes us to acknowledge his love and even now to live our whole life in relation with him. This relationship lasts forever.