Is it possible for us to really be happy and joyful that others are experiencing happiness and joy?
Mudita is being happy because others are happy. This is sometimes not easy because the opposite of this quality of Mudita is jealousy and envy, especially when you see others doing better than yourself.
Another aspect of Mudita is making an effort to make others happy. In a way one can relate it to Karuna because when you see others suffering you try to do something about it and to get them to experience some joy and lightness, freed from their suffering.
Now sympathetic joy or Mudita has another interesting aspect, which is learning to rejoice, learning to be happy about your own happiness. Though again this sounds simple, in practice sometimes for some people it is not easy. I know some people who when they experience happiness and joy say: I don’t deserve this, I’m such a bad person, I don’t deserve to be happy. And I know others who say: How can I feel happy? I feel guilty because there is such a lot of suffering around me so how can I experience joy? When I experience joy I feel guilty about it. Therefore it is extremely important to learn to develop this quality. To rejoice in your own happiness, to rejoice in your own goodness, to rejoice in seeing more and more the positive in yourself; and when you see more and more the positive in yourself, then you are bound to see more and more the positive in others.