Joy is more than circumstantial happiness. It's something we can experience even in the midst of troubles.
Galatians 5:22-23 (NLT2) 22 But the Holy Spirit produces this kind of fruit in our lives: love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness, and self-control. There is no law against these things!
Nehemiah 8:10 (NLT) And Nehemiah continued, “Go and celebrate with a feast of rich foods and sweet drinks, and share gifts of food with people who have nothing prepared. This is a sacred day before our Lord. Don’t be dejected and sad, for the joy of the LORD is your strength!”