In the Christian life, joy and sorrow overlap.
2 Corinthians 6:10 (NKJV)
...sorrowful, yet always rejoicing...
Over and over, the Bible commands us to rejoice. It's the goodness of Jesus and knowing that He's always in control that allows us to do so when we suffer, hurt and experience loss.
1 Peter 1:3-7 NLT
3 All praise to God, the Father of our Lord Jesus Christ. It is by his great mercy that we have been born again, because God raised Jesus Christ from the dead. Now we live with great expectation, 4 and we have a priceless inheritance—an inheritance that is kept in heaven for you, pure and undefiled, beyond the reach of change and decay. 5 And through your faith, God is protecting you by his power until you receive this salvation, which is ready to be revealed on the last day for all to see. 6 So be truly glad. There is wonderful joy ahead, even though you have to endure many trials for a little while. 7 These trials will show that your faith is genuine. It is being tested as fire tests and purifies gold—though your faith is far more precious than mere gold. So when your faith remains strong through many trials, it will bring you much praise and glory and honor on the day when Jesus Christ is revealed to the whole world.