I once had a job that involved standing in a prominent, but non-specific spot for an extended period of time. As long as I was easily visible and could see a specific area well, I could stand anywhere I wanted. It was not a job with a demanding list of qualifications.
Anyway, I had one coworker who insisted on standing right next to me, within my personal space. They often stood so close that we were touching. Again, bear in mind, they could stand anywhere in a thirty square yard space, and they chose to stand on top of me.
I did the only think I could do. I made a game out of it. I would slowly move away, forcing the other person to follow me. Once, when I got tired of just doing laps of the area, I got them to follow me in a figure eight pattern.