There is a difference between joy and happiness. Happiness comes because of external reasons, such as a brand new car, a promotion at work, or winning the lottery. On the other hand, joy comes because of internal reasons. What are those reasons?
The first reason to have joy is salvation. A person who already knows his destiny because of Jesus’ sacrifice will have an inexplicable amount of joy. He knows that whatever happens in this life, they are all temporary, and that God would one day bring him to heaven.
Another reason for joy is God’s current blessings. Blessings do not always come in physical or material wrapping. Some blessings are intangible, like God’s protection, understanding of God’s word, satisfaction in life, and the power to forgive. All of these things give joy, and unlike happiness, it will last.