Writing a novel is an incredibly free experience. One puts one's self in a narrative mode. You can go off in any direction - the past, the future, or go laterally, or include one's own beliefs. It's total freedom.
Happiness and joy are not the same. For what does the fervent craving for joy mean? It does not mean that we wish at any cost to experience the psychic state of being joyful. We want to have reason for joy, for an unceasing joy that fills us utterly, sweeps all before it, exceeds all measure.