Ps 68:3 ~ "But let the righteous be glad; Let them rejoice before God; Yes, let them rejoice exceedingly."
Jas 1:2 ~ "My brethren, count it all joy when you fall into various trials,"
1 Jo 1:4 ~ "And these things we write to you that your joy may be full."

As Christians we should be filled with more joy than any other people group. For we alone are partakers in the glorious salvation of the Lord Jesus Christ. Above are a few verses that explain why we should be joyful, and in whom and what we should be joyful. In psalms we are encouraged to be filled with joy for God is our defender. He melts our enemies like wax and we should be joyful in this protection. In James we are to take joy for our trials are producing patience and is perfecting our character. There are so many reasons that we should be joyful. For God's blessings, provision, direction, commands, laws, statutes, holiness, suffering, righteousness, etc. etc. And most importantly for Christ's ultimate salvation for us.

Application
1. Pray that God would fill you with a deeper joy rooted in Him.
2. Even in hard times consider how God is growing and perfecting you.
3. Encourage others and share your joy.