Joy unspeakable, is indeed the fruit of the Holy Spirit. Joy is the second mentioned, out of nine fruit of the Spirit, (Gal 5:22). It is the very nature of the Holy Spirit. A person who has the Spirit within him surely has the joy of the Holy Spirit. It is an evidence of the presence of the Spirit within an individual. Joy of the Lord is an inner feeling of pleasure and delight that cannot be attributed to any happenings or circumstances around you, but to the relationship one has with the Spirit. It is an assurance of God's presence with you no matter the circumstances. It is what keeps you going when the storms of life are raging.
Sometimes, people confuse joy in the Spirit with happiness. Happiness results from attainment of what one considers good, but the joy of the Spirit results from an in-filling of the Holy Spirit. Happiness is characterized by good luck or fortune. This means that when there is misfortune, happiness disappears and misery sets in - it is momentary.
However, this is not the case with Christian joy; even when there is a misfortune, the person is still joyful. Certainly, the person acknowledges the mishap but is not moved or discouraged by it. Joy in the Spirit boosts one's resilience.
Joy of the Spirit is first secured by accepting the Lord Jesus as your saviour. At salvation, you are filled with the Holy Spirit and you receive the joy of the spirit, (Rom 5:11, Psalm 51:12). Subsequently, we are refilled repeatedly by dwelling in God's presence (Psalm 16:11), in praise and worship (Psalm 22:3), in the study of the Word (Jer 15:16) and in having fellowship with brethren (Matt 18:20). When the Spirit has more control over you, you will experience more of the Christian joy. Dwelling in God's presence makes you to become more conscious of God, of His power, love, nature, etc., and in the process you are filled with His Spirit.
There is so much to benefit from being filled with the joy of the Spirit. One of which is that you are strengthened (Neh 8:10). At times, the road may be steep, rough, crooked and the destination far; the joy of the spirit enables you to overcome all odds and to reach your destination. Furthermore, Christian joy replaces mourning in one's life (Isa 61:3). You will not sorrow like them that do not have hope. In addition, joy in the spirit ensures fruitfulness and abundance (Joel 1:12) because it is only with joy can you receive answers and directions from God (Isa 12:3).
In the scriptures, character examples have been written down for us to follow and emulate. One example is Joseph, who had a dream where he was superior to his parents and siblings but he had to go through slavery and prison before realising his dream. The Christian Joy he had enabled him to help the two employees of Pharaoh who had dreams in prison and were sad because they could not interpret their dreams. Joseph's willingness to interpret their dreams despite his situation led to his freedom and realisation of his dream (Gen 40, 41).
The joy of the Lord is the conqueror's backbone. It is a characteristic of those that trust God. The joy of the Lord guarantees victory over the challenges of life. As fish cannot survive outside water, so also, a child of God cannot survive without joy: the fruit of the Spirit. It is available even now.