I think this is a really good definition of joy:
JOY IS THE OUTWARD EXPRESSION OF THE HOPE THAT IS IN US.
Luke 2:10-11 gives us insight into how God has designed us to understand joy:
And the angel said to them, “Fear not, for behold, I bring you good news of great joy that will be for all the people. For unto you is born this day in the city of David a Savior, who is Christ the Lord."
Over and over in the birth narratives, people are told not to fear. Jesus Christ is the center, the foundation, the wellspring, the most perfect reason for joy in our lives. Do not fear…a great joy…does it get any clearer than that?
How has God designed us to express joy? What is the primary way God has called us to express our joy in Christ?
Luke 2:12-14 tells us how:
"And this will be a sign for you: you will find a baby wrapped in swaddling cloths and lying in a manger.” And suddenly there was with the angel a multitude of the heavenly host praising God and saying,