Like the Samaritan we should be thankful for the blessings God gives us. I wondered if the demand to be thankful could imply that without thankfulness a person could stand condemned in the sight of God. In the end, the continual weight of this type of moral demand must inevitably condemn, even condemn the simple heart of a child. We should be thankful, but then thankfulness is a natural response of the heart. You can't really tell someone to be thankful, they would be putting on an act.
Thankfulness comes from within.
The thanks and praise of the Samaritan was a natural response for the free and undeserved mercy of God which was his in Christ, just for the asking. He didn't earn the kindness of God. He just asked for it and it was freely given. He knew he couldn't earn it, he was an outcast, a Samaritan. So having accepted God's grace, thanks and praise was his natural response.