Thankfulness

"This is the virtue characteristic of real Christians; it is their worship of God at its best. They thank God and do it with all their heart. This is a virtue unattainable by any other human being on earth... to thank with all your heart is an art--an art which the Holy Spirit teaches. And you need not worry that the man who can really say Deo gratias (to God be thanks) with all his heart will be proud, stubborn, rough, and tough, or will work against God with His gifts."
(from Luther's exposition of Psalm 111:1)

"To begin with, we must rejoice at the less important good things (exiguis bonis) which we enjoy according to the Second Table of the law in that our bodies an possessions are protected. For these gifts are of minor importance when compared with those which we enjoy according to the First Table: that God has revealed Himself, has made known what He intends to do with us, gives His Word, grants faith and the Holy Spirit, hears prayers, daily increases His church, etc. These things are so great that no tongue is able to amplify and praise them as they deserve.. to this David turns his eyes; on this he meditates, and so he is moved to gratitude... For only those are truly thankful who receive the gifts of God joyfully and rejoice in the Giver." (on Psalm 122).