If you want to do one good thing in the world, the best thing you can do is give other people joy.
Master said if you want to be happy no one in the world can take happiness from you; if you want to be unhappy, no one in the world can make you happy. So choose to be happy.
Understand that there is no relationship between your inner happiness and your inner joy and the outer things that you experience and behold in the world, that it all begins with you, the world is a mirror to your own Self, when you can look at things and feel joy not in the things but in yourself.