Updated: Apr 8, 2019
"Rejoice in the Lord always: and again I say, Rejoice." (Philippians 4:4)
Joy is a fruit of the recreated human spirit, something that's inherent in you. It doesn't matter what news or event tries to make you unhappy-- you can always be joyful in the Holy Spirit, for such is the Kingdom of God.
"...for the kingdom of God is not eating and drinking, but righteousness and peace and joy in the Holy Spirit."
Ephesians 5:18-19 also reveals how you can be full of the joy of the Holy Spirit always.
"And do not be drunk with wine, in which is dissipation; but be filled with the Spirit, speaking to one another in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord"
This one one of the Apostle Paul's secrets of success; he wrote what we read in our opening verse, while in prison. He was full of joy, and continued preaching the Gospel in prison. In his letter to Ephesus he asked them to pray:
"and for me, that utterance may be given to me, that I may open my mouth boldly to make known the mystery of the gospel, for which I am an ambassador in chains; that in it I may speak boldly, as I ought to speak."
Notice the underlined portion: he didn't allow his experience to dictate his mood or interfere with the joy of the Lord in his heart.
In your life, see challenges as opportunities to manifest the glory of God, that way you'll always be full of joy.
"My brethren, count it all joy when you fall into various trials..."
"And we know that all things work together for good to those who love God, to those who are the called according to His purpose."
The Word should form the basis for your joy at all times. When you interpret and respond to situation based on God's Word, you'll discover that nothing in life could give you a bad day, or be to your disadvantage, because your joy comes through the Word and the Spirit of God.
The Lord Jesus, through His vicarious death and triumphant resurrection, has brought me into the life of unlimited joy, victory, dominion, and righteousness. Therefore, I rejoice evermore, with joy unspeakable, and full of glory. My joy is from the Holy Spirit, and it knows no bounds. Hallelujah!
Further Study: Nehemiah 8:10; 1 Peter 1:8; Isaiah 12:3