Joy and sadness always remain together. They are the best buddies. Just joy or sadness alone does not lead to development of the deepest and profound emotions and thought. Only when they come together that they create a deep emotional tag to the memories. This tag creates us, our being our personality and then guides our actions.
The guide to our being is to look deep inside us, realise that we are not just looking for joy. Just happiness cannot make us complete.
So the question is are we really looking to be happy. Or just complete.