Ask HN: How do I tell my employer I love the job but hate what I'm working on?

I am working a job I love. I work for decent pay in a location close to home with people I like. However, one of my assigned tasks is causing me so much grief that I would rather leave the company than endure another minute. I absolutely hate it. The thing is, I'd like to tell them this in a productive manner as I wish to continue my other work (and maybe additional work), but I am _miserable_ doing this one specific task.

How do I tell my employer that I like it here but find myself drained and unmotivated about one of my assigned tasks?