James 5:13 (KJV)
Is any among you afflicted? let him pray. Is any merry? let him sing psalms.

No interpretation is necessary. In either case, focus on God
In affliction, through prayer
In joy, through singing to the Lord

(psalms is not necessarily a reference to the book of Psalms.
"Thayer Definition:

1. to pluck off, pull out
2. to cause to vibrate by touching, to twang
   2a) to touch or strike the chord, to twang the strings of a musical instrument so that they gently vibrate
   2b) to play on a stringed instrument, to play, the harp, etc.
   2c) to sing to the music of the harp
   2d) in the NT to sing a hymn, to celebrate the praises of God in song")