We must understand that praise is not motivated by emotion, but by our choice. What this Scripture is saying is that it actually befits God's people, and is a becoming characteristic to be a people of joyfulness and praise. We praise Him for who He is, not for the circumstances. We recognise that He is greater than any situation, and give Him our praise even in the midst of troubles. Praise can also be a powerful weapon when properly understood.
Darkness is vanquished in the presence of light.
The Old Testament gives illustration of this when the Israelites defeated a vast army simply by praising God. Multitudes of Moabites and Ammonites were prepared to attack the Israelites. King Jehoshaphat was afraid and sought the Lord. When they began to sing and praise, the Lord caused the opposing armies to be routed. Our praise can bring victory to our lives.