What should I do when teaching maths for unmotivated undergraduate students?
Start each session with a quiz.  Have students exchange papers to grade.  Have full hour tests every 1-2 weeks.  Do lots of in class exercises that students work on.  (Put the animals to work.)

Emphasize calculations and problem solving.  Not theorems.

Emphasize efficiency in terms of grading exams.

Follow the text closely and spend minimal time on your lecture prep.