Answer: The joy of many is positive, beneficial, and easily achieved. We are talking about spiritual joy, of course, which exists above time, increases in pleasure, and does not disappear.
The joy of many occurs when I fill everyone else, and each of them fills the others and me. In this manner we intensify our fulfillment and joy within each person. I delight in the joy of others, they delight in my joy, and, together, we multiply our inspiration and reach a Light that is 620 times more powerful than the Light at the beginning of creation. We can receive all this and enjoy it in our world.
Due to an event like the Convention, in the connection between us we reveal such a Light, such a spiritual power, and joy that we will reach the level of Infinity! And one must reveal this during his lifetime.
From Kabbalah for Beginners, "Happiness" 10/28/10