The joy of serving God is itself a very important aspect of divine service, to the point that one who does not serve God with joy is liable for punishment. Joy in the performance of mitzvot sometimes necessitates humility and self-abnegation, which are praiseworthy. One whose concern for his personal honor prevents him from serving God with wholehearted joy is considered a sinner and a fool.

The joy that a person experiences when performing mitzvot and in loving God, who commanded them, is a great [aspect of divine] service. Anyone who withholds himself from this joy deserves punishment, as the verse states: “Because you did not serve the Lord your God with joy and with gladness of heart” (Deuteronomy 28:47). Anyone who is haughty, concerned with his honor, and who views himself with self-importance in these areas is a sinner and a fool. King Solomon warned about this, saying: “Do not glorify yourself before a king” (Proverbs 25:6). Anyone who lowers himself and treats himself lightly in these areas is a great and honored person who serves with love. This is what King David said: “And I would be demeaned even more than this, and I would be lowly in my eyes” (II Samuel 6:22). The only greatness and honor is to rejoice before God, as it is stated: “King David was leaping and dancing before the Lord” (II Samuel 6:16). (Rambam, Mishneh Torah, Sefer Zemanim, Hilkhot Lulav 8:5)

Joy opens up all the gates of wisdom and divine inspiration. The joy that accompanies fulfilling God’s commandments is greater than all of the pleasures of this world.

Each and every mitzva that one encounters is a gift sent to him by the Holy One, blessed be He, and the greater his joy [in performing the mitzva], the greater will be his reward. This is what the pious rabbi, the kabbalist, our teacher, Rabbi Yitzĥak Ashkenazi [the Arizal] of blessed memory, revealed to his confidant: That all that he had achieved, that the gates of wisdom and divine inspiration that had opened for him, was as a reward for being infinitely joyous over each mitzva that he performed. He said that this is the meaning of the verse [which states that Israel will be punished] “because you did not serve the Lord your God with joy and with gladness of heart, due to abundance of everything [merov kol]” (Deuteronomy 28:47). The explanation of the phrase merov kol is: More than all the pleasures of the world, and all the gold, precious stones, and pearls. (Rabbi Elazar Azikri, Sefer Ĥaredim, Introduction)

Judaism does not advocate a life of sadness and sorrow. On the contrary, one of Judaism’s lofty goals is to live joyfully. Joy is a necessary precondition for divine revelation, and it is also a natural result of contemplating the truth of God’s Torah and mitzvot.

Judaism has never advocated pain and mourning, abstinence and sorrow, as being among its lofty goals, and certainly not as the height of its aspirations. On the contrary, happiness and joy, exuberance and gladness are its loftiest goals. The Divine Presence does not rest among Israel through lethargy and pain, sadness, depression, or frivolousness. Only where joy has sought to dwell is an appropriate setting for God’s presence. Frivolousness distances a person from the seriousness that characterizes the divine law, while the truth inherent in Torah is exciting, and chases away sadness, pain, and depression. It instructs and accustoms us to live a rich life full of exuberance and bliss [while still] on earth. (Rabbi Samson Raphael Hirsch, Bema’agalei Shana 2, p. 98)