Some editions of the ArtScroll siddur have the following instruction before Yehi Khevod (in pesukei dezimra):
The following prayer should be recited with special intensity.
What is the source for this?
Sidur Bes Yaakov (Emden) says of this paragraph:
אומרו במתון וכונה ושמחה
Say it with calmness, direction of thought, and joy.