This Psalm reveals an amazing truth. Part of the cause for the Spreading Gospel to all unbelieving nations, is the blessing of God on His People. Said another way, 

God's blesses us so that the world may know Him and be saved!

This challenges our motive for asking for His blessing. We miss the boat when we see blessings as an end in themselves. Every good thing we receive is a gift from Him. And the reason we have received is to further enable us to proclaim His Name, as we "shine like stars in the dark universe, holding forth the Word of Life"