Brainstorm a list of WIIFM ('What's in it for me?') from a student perspective. If you cannot think of more than “because you should know it”, then you need to talk with your learners and get a better sense both of where they are in their learning and where they are going.
If you know your students well but you still have a hard time determining the relevance of a topic, perhaps consider removing that content from your course. Sometimes, what excites you might not be what excites them.
As evidence of completion, please add your WIIFM list (and any reflections on this) to your Extend NZ blog or portfolio.