Joy is not dependent upon outward circumstances. Joy is something that we can have under all circumstances when we are sad or happy. Outward circumstances are always neutral. They seem to be happy or sad according to the happy or sad attitudes of the mind.
Happiness is an attitude of mind, born of the simple determination to be happy under all outward circumstances.
A deliberate attitude that you have to hold in your mind as one of the basic rules of yoga is to remain even-minded and cheerful.
Happiness is self-generated. It depends on one's attitude of mind. The basis of happiness is the simple fact that the deepest reality of our own nature is ever-existing, ever-conscious, ever-new joy.