Joy is the serious business of Heaven. That statement comes from Letters to Malcolm: Chiefly on Prayer by C. S. Lewis. When I first read that statement years ago, when my relationship with God was shallow and fragile and I viewed His "rules" as restrictive and punitive, I took it as yet another way that God sucked the fun out of everything. At that time, I viewed a life of obedience to God as boring and the required change in behavior as robotic. Oh, how wrong I was! As I have grown closer to God, I experience more and more levels of peace and happiness.
Lewis is not saying that Heavenly joy is a burden that must be systematically manufactured. No, quite the opposite! He is saying that the joy we feel in our lives now is deemed as frivolous or unproductive but dancing and singing is what Heaven is all about. Being joyful is the "work" we will perform in Heaven. How amazing is that?