cultivating mudita
Mudita is a Buddhist term that loosely translates to sympathetic or unselfish joy and encourages us to find happiness in the wellbeing of others. Mudita is described as an inner wellspring of joy that is always accessible. It extends to all beings, not just to those close to us and may be the antidote to jealousy and comparison.
Similar to metta (loving-kindness), in developing mudita we appreciate others as complete and complex beings, helping us to release any judgement of their character.
Practising Mudita
Mudita can be cultivated through intensional meditation, in which you should not focus on someone dearly loved, disliked or someone you feel neutral about. Instead, center your awareness on a good friend with a warm cheerful nature. Contemplate this cheerfulness with appreciation and let it fill you until the state of sympathetic joy (mudita) is strong. Then begin to direct this joy towards a loved person, a "neutral" person, and a person you have a difficult relationship with.
The next stage is to develop impartiality among the four--the loved one, the neutral person, the difficult person and yourself. From there, sympathetic joy is extended to all beings.
Adapted from:
O'Brien, Barbara. "Mudita: The Buddhist Practice of Sympathetic Joy." Learn Religions, Sep. 1, 2021, learnreligions.com/mudita-sympathetic-joy-449704.