Suggestions for teaching solfège to an adult community choir?

People join community choirs as adults for several reasons, and I’ve found that learning a new pedagogical language like solfège is not very high among them. But I want to help singers gain confidence, independence, and skill, so I’m looking for tiny, every-rehearsal steps to enable them to use this practice. But I want to keep the joy, passion, dedication, and transcendence in rehearsals, too. What has worked for you?