First, on any engineering courses the students take for granted the need for math/science. That's not your case, so take some time every class to explain why and how this could be useful for your students beyond passing the grade
Second, they usually had a very hard time with school math, so take it easy and by all means try to avoid showing how smart you are when dealing with the abstractions and the logic, instead focusing on how little is needed to cover most of your material.
Third, they don't enjoy the solution of very difficult problems or challenging exercises (like a science/engineering student does.) They really enjoy the simple fact of grasping the concepts and making something useful with that
Fourth, check your students' background. Be prepared to provide several high/elementary school sessions.
fifth, your students are very good for reading, so give them some literature partially related to math (for example a biography of Descartes showing some of his math discoveries.) That's a pretty good way to generate interest. If they're political interested, then talk about Marx's math manuscripts, etc.
