Love and joy are likened to a cup which sits on the platter of the World; only when the cup is full to the brim can you begin sending it into the world. The depth of that cup -- the quality of its fullness -- is carved by the will to experience and abide with certain sorrow. By this I do not mean the "sadness" of a bad time or the "frustration" of thwarted desire, or the "misery" of suffering; I mean the sorrowing that is simultaneous with joy in complete feeling. This depth of feeling is not "serious" and is not "somber" and perhaps sorrow is the wrong name for it, but it is a sorrow that permits laughter; a sorrow that shames the glee of irresponsibility; the sorrow of love lifting its weight of ownership in the world. It is NOT a sorrow of resistance but a sorrow of passion feeling the Shadow as surely as it feels the light.
This is not sorrow that can be found clinging within an identity, having to do with an "I" seeking goals and avoiding losses.
It is more the tranquil reflection of Aware Will knowing that the Dark and Light sides of the Force are brothers, not enemies.
To the depth of your ability to sense and abide with these feelings wherever you find them, will come your capacity for joy and the highest, simplest, purest diamond flame of Life.