In the same situation as you. Working through a labour hire company. Cleaned up chicken leftovers at a plant and moved the lite n easy microwave meal trays from a conveyor belt to a machine that put the lids on. That was fucked. About 4 years ago now, and i've had a bad shoulder ever since.
I did some landscaping work too, but it was in a all girls school. Plus i had to sort out there laundry one day haha.