Mudita
Muditā is a dharmic concept of joy, particularly an especially sympathetic or vicarious joy—the pleasure that comes from delighting in other people's well-being.
Application
Mudita meditation cultivates appreciative joy at the success and good fortune of others. The Buddha described this variety of meditation in this way:Thus, mudita is also referred to as 'unselfish joy'. The cultivation of virtues is manifested in the way that Buddhism is lived and practiced. Gavin Douglas notes that mudita and metta are 'associated with the act of sounding and hearing the bells' by the pagoda.
Mudita is traditionally regarded as the most difficult to cultivate of the four immeasurables. To show joy is to celebrate happiness and achievement in others even when we are facing tragedy ourselves. Sayadaw U Pandita notes that mudita does not consist of false joy or envy. This means that deriving pleasure from the misfortune of others is not mudita, and neither are 'deceitful smirks' and 'false compliments'.
The "far enemies" of joy are jealousy and greed, mind-states in obvious opposition. Joy's "near enemy", the quality which superficially resembles joy but is in fact more subtly in opposition to it, is exhilaration, described as a grasping at pleasant experience out of a sense of insufficiency or lack.