It is only when we come to total and unconditional "love" of our own darkness that we can know God incarnate in us, loving and understanding us in our totality. Pascal says that no one can love God without knowing their own misery.
We know joy when we are happy to take from life what is given. When we experience the joy of the soul and higher states of consciousness, this joy is the essence of completion and fulfillment. There is nothing that can add to it or take away from it. Joy is our natural state.