Rejoicing means taking pleasure in others' good fortune. If we see someone resting for a moment in a comfortable spot, drinking cool water or enjoying the sun on her face, we rejoice in her happiness and wish that it might increase. We pray that by the power of our wishes, prayers, and pure heart, her happiness will grow unceasingly. Whether it is someone's moment in the sun, new clothes, nice car, or winning lottery ticket, we are happy for her. We don't give in to envy, thinking, "I wish I had a red car like that one." Nor are we resentful, wondering, "Why does she get to drive around in such style?" When we truly rejoice, we leave no room for jealousy, competitiveness, or self-centeredness. In fact, rejoicing in the happiness of others is the antidote to jealousy.
We rejoice not only when others are happy in the moment, but also when they plant seeds of future happiness; this increases the merit resulting from their virtuous act. We also rejoice when someone on the spiritual path prays, meditates, and creates virtue and we never do anything to interfere.
— Chagdud Tulku Rinpoche, Change of Heart by Lama Shenpen Drolma, editor