From The Progress Principle:
Over the past 15 years, we have studied what makes people happy and engaged at work. In discovering the answer, we also learned a lot about misery at work. …
What we discovered is that the key factor you can use to make employees miserable on the job is to simply keep them from making the progress they expect to make in meaningful work.
People want to make a valuable contribution, and feel great when they make progress toward doing so.