The very first tendency of our minds is towards something in as far as it is good. The adage of the world is, “If it feels good do it”. Now there is a bit of truth in this statement. This tendency to what is good is caused or effected by love. So love is the first of our emotions and the root of them all.
Among the fruit of the Holy Ghost, Charity is listed as first. This Charity is given to us in a special manner, as it is given to us in the likeness of the Holy Ghost, since the Holy Ghost is Love. As St. Paul says, (Romans 5:5): "The charity of God is poured forth in our hearts by the Holy Ghost, Who is given to us." The Father begets the Son Who is the Word of God, the living expression of the Father. The Father see the Son and Loves Him as Himself and this Love is something tangible, that is, the Holy Ghost. The Holy Ghost is breathed forth so to speak.
The result of the love of charity is joy: because every lover rejoices at being united to the beloved. "He that abideth in charity, abideth in God, and God in Him": wherefore the sequel of charity is "joy." Thus to fornication, which is the love of satisfying lust outside lawful wedlock, we may contrast charity, whereby the soul is wedded to God in a 'true love' union, unlike the union of lust.
So flowing from this union we feel joy as a result. True love brings true joy. Opposed to this is uncleanness which put our hearts and mind in a state of disturbance taking away the tranquillity of joy.
The Greek word for 'joy' is Kevo, derived from the word charis, which is the Greek word for 'grace.' This is significant to note, for chara is produced by the charis of God. This means 'joy' is not a human-based happiness that comes and goes but, rather, true 'joy' is divine in its origin. It is a Spirit-given expression that flourishes best in hard times. For example, in 1 Thessalonians 1:6,the Thessalonians were under great stress due to persecution; yet in the midst of it all, they continued to experience great joy. The Greek strongly implies that their supernatural joy was due to the Holy Spirit working in them. Paul even called it the "joy of the Holy Ghost".
So we see that these two fruits that flow from the gifts, give us that sensible joy and love to serve God with all our hearts