When I was growing up there was never any doubt in my mind that the only mood appropriate for worship was happy. As the Creator, God was the natural object of our worship. As the created, it was natural to feel that a happy joyful spirit was the only way to approach God. Anything less would dishonor him.
This is a companion discussion topic for the original entry at https://spectrummagazine.org/article/joan-hughson/2011/08/09/worshiping-god-praise-and-lament