The Master of Joy
Simcha
The Chozeh explained that a person who has a joyous event in his life is called a baal simchah, literally a master over joy. At that moment he has the ability and the opportunity to be in charge of all matters of happiness and joy. He is then granted the power to give joy to others and gladden them with an abundance of shefa and blessings.
Source: Ramasayim Tzofim 39b