Joy in Scripture is a deep, abiding gladness rooted in God's presence and salvation, distinct from circumstantial happiness. It is a fruit of the Spirit and the strength of God's people, even in trials.
Nehemiah 8:10
Then he said unto them, Go your way, eat the fat, and drink the sweet, and send portions unto them for whom nothing is prepared: for this day is holy unto our LORD: neither be ye sorry; for the joy of the LORD is your strength.
Although the fig tree shall not blossom, neither shall fruit be in the vines; the labour of the olive shall fail, and the fields shall yield no meat; the flock shall be cut off from the fold, and there shall be no herd in the stalls:
Yet I will rejoice in the Lord, I will joy in the God of my salvation.
Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God.
Jesus... who for the joy that was set before him endured the cross.