Psalm 122 is one of the "Ascension Psalms" or "Psalms of Ascent," which would be sung by pilgrims on the way to worship in Jerusalem.
Psalm 122 is most akin to a "hymn"
It begins with an expression of glad praise (vv. 1-2)
It continues by listing the reasons for that glad praise (vv. 3-5)
It concludes with a call to response (vv. 6-9)
Verses 3-5 depict what gathered worship OUGHT to be.
Verses 6-9 lead us to respond to what gathered worship ACTUALLY is.
PRAY (vv. 6-7)
THINK OF OTHERS (v. 8)
BE THE GOOD YOU WANT TO SEE (v. 9)