I saw this thought-provoking thread "What do you like most about your job" at https://www.proformative.com/questions/what-do-you-like-most-about-your-job and felt it warranted the flip side of that question.
I'll kick things off. I least enjoy staying on top of and complying with ever-changing government regulations. The volume, complexity, cost and anxiety takes much of the fun out of it.
Feel free to answer anonymously.