My thesis is that in the Scripture when God "blesses" men they are thereby helped and strengthened and made better off than they were before, but when men "bless" God he is not helped or strengthened or made better off. Rather (with C. A. Keller in THAT, I, 361) man's blessing God is an "expression of praising Thankfulness" - John Piper |desiringGod
I love that! I love to think that saying Bless the Lord is a way of saying, "THANK YOU!" It makes me like this design even more!