James J. Martin S.J. is a writer and the Culture Editor of the Jesuit magazine America. His book My Life with the Saints (2006) was named by Publishers Weekly as one of the "Best Books of the Year" and was the winner of a 2007 Christopher Award.
YouTube has a series of 11 videos of Fr Martin's presentation called "Laughing with the Saints: Joy, Humor and Laughter in the Spiritual Life". I enjoyed watching these enormously.
During this presentation, Fr. Martin quotes Saint Teresa of Avila: "A sad nun is a bad nun." The same could be said of catechists - a sense of humor is one of the essential qualities of a good catechist.