I have a few questions of my own. First, what are you teaching? Second, why do the students need to learn it? That is, have you invested them in the topic? Third, when students find a given task too difficult, it's best to give them a task that you know they can do in order to build up their confidence. Have you tried that?
As you know, we teach people, not subjects. If you focus on your students' needs first, the rest will eventually take care of itself.