Two things that might help. First is acknowledging that the benefit of a joke isn't just the humor, it's making yourself look funny. If you notice and factor out the part of you that wants to seem funny, fewer jokes will cross the threshold of being worth saying. (Maybe 10% fewer. :) The second is the understanding that jokes disrupt a conversation. A conversation is a collective effort that creates a certain mood, and unless entertainment is the main goal of the conversation, then jokes have a cost. They hinder people from what they're trying to do.