Lack of humor comes from a deadly serious attitude. If you are not meditating properly, sitting still and upright, you think there will be someone standing behind you with a sharp sword, just about to strike. This is the self-consciousness of watching yourself. Actually it is not Big Brother who is watching; it is Big Me! Another aspect of me is watching me, behind me, just about to strike, just about to pinpoint my failure. There is no joy in this approach, no sense of humor at all.
“Sense of Humor” in Cutting Through Spiritual Materialism, page 129, the Shambhala Library Edition.