There are lots of things that contribute to enjoyable work. Giving people the feeling their time isn't worth anything is probably the best deterrent. Stuff like: being late to pick people up; having them show if there is nothing to do and have them sit and wait for 8 hours doing absolutely nothing; similarly, having people sit and wait after the work is done (Extra points if they also act as if they did you a huge favor!); shit tools and materials requiring a lot of extra work every day to save 10 euro; insufficient time to do a decent job; treating any kind of communication as disruptive.

In a call center you give people 30 sec to 2 min to recover after a bunch of calls. If you take that specific moment to complaint people don't know how fast to gtfo.