How to train Rejoicing Joy in others Success?
When sitting alone, in silence, each early morning, with closed eyes one wishes:
May I radiate, and meet
with only never-ending, and mutually rejoicing joy!
May
I and all the various beings on the 31 levels of existence develop
and find
only celebration, and elation in a never-ending mutual joy in
other's well-being!
May
I and all beings on the sense-desire, fine-material,
and the formless plane
develop and encounter this generous, infinite, and mutually rejoicing joy!
May
I and all beings in the front, to the right, the back, the left,
and below as
above, develop, and experience open-hearted, sharing, and mutually rejoicing joy!
May I
and all beings within this city, country, planet, and multi-verse always:
Be fully aware and deeply mindful of this content and mutually rejoicing joy!
Examine all details
and aspects of this satisfied and mutually rejoicing joy!
Put enthusiastic effort in our praxis of this devoted mutually rejoicing joy!
Enjoy enraptured jubilant gladness in this exulting mutually rejoicing joy!
Be silenced by the tranquillity of quiet, and all smiling mutually rejoicing joy!
Be concentrated
and absorbed into one-pointedness by genuine rejoicing joy!
Dwell in
an imperturbable equanimity of pure, and mutually rejoicing joy...
Yeah! May
it be even so, since mutual joy causes the jewel of contentment!
Mutual Joy Audio
Dhamma-Talk: Rejoicing evaporates all Envy and Jealousy..
https://soundcloud.com/bhikkhu-samahita/mutual-joy-causes-contentment

Crucial
Comment: Mutual Joy is the 3rd infinite mental state (Appamaññā):
This gradually reduces all envy, jealousy, possessiveness, stinginess, avarice,
miserliness, green covetousness,
and any unhappiness related with all these states.
The cause of Mutual Joy is rejoicing in your child's or boon companion's
success.
This same joy can then be beamed towards all liked,
neutral and also hostile beings.
Mutual Joy is then the
proximate cause
of all satisfied and fulfilled
Contentment...
Lack of
mutual joy is thus the
proximate cause
of
all
dissatisfied discontentment...
Joined with the 7 links to Awakening it will later cause a formless
jhāna...
Be happy at all, and especially other being's success! Then calm comfort grows!

More
on
Mutual Joy
(Mudita):
Rejoicing Bliss = Mudita,
Infinitely_Joyous_Consciousness,
Safe_Medicine,
Rejoicing_Joy,
Mudita: Unselfish Joy