Sometimes we wake up on the wrong side of the bed, as they say. Meaning we just feel grumpy and miserable. Maybe you find yourself in a hard situation and don't see any way out. Others may feel overwhelmed or going through sorrow due to a loss of a loved one.
As a result, we just don't feel like rejoicing. We don't see any reason to rejoice at that moment in time.
When we don't feel like rejoicing we need to tell God just how we truly feel. He's not going to struck you down for it. He already knows but wants to hear you admit it. As you tell him just how you feel , God will give you reasons to rejoice.
Psalm 118:24 says, "This is the day that the Lord hath made; let us rejoice and be glad in it."
Psalm 118:1 says, "Give thanks to the Lord, for is good; his love endures forever."
The Bible which is God's Word has many verses which tell us to rejoice. I can't list them all but I'm sure you can think of some also.
I'm rejoicing that I can serve God today as he woke me up and I have another day to do so. The same for you! What would God have to you do today for His kingdom?