A keen insight on the nature of joy from Henri J. M. Nouwen:
“Joy does not come from positive predictions about the state of the world. It does not depend on the ups and downs of the circumstances of our lives. Joy is based on the spiritual knowledge that, while the world in which we live is shrouded in darkness, God has overcome the world. Jesus says it loudly and clearly: ‘In the world you will have troubles, but rejoice, I have overcome the world.’ ” 
We can rejoice even during the tough times because we know that in the end, “God’s light is more real than all the darkness, that God’s truth is more powerful than all human lies, that God’s love is stronger than death.”  I pray that you may find joy.
  Henri J. M. Nouwen, Hear and Now: Living in the Spirit (New York: The Crossroad Publishing Company), 39-40.