Namely, your lower back.
I destroyed my body on Monday by stubbornly opting to do the following:
* Lifting a dishwasher, by myself, onto a mat and moving it out of the kitchen.
* Somehow maneuvering / lifting a fridge onto a mat, by myself, and moving it out of the kitchen.
* Moving a gigantic pantry, by myself.
* Sanding the walls.
* Painting the walls.
* Installing new flooring.
All in one day.
It's Wednesday night and I'm only now starting to feel less pain.
Don't try this at home.