Just as a funny aside, I was doing my wall run workout the other day (I am a long way from getting to ten minutes, but slowly increasing my time), and was doing well. Afterwards, I felt a particular, but not unfamiliar, pain on the top of my feet. I had been doing the wall runs barefoot against a wall in the garage, which is textured and painted drywall. The friction from the rocking motion was enough to wear off the skin. Ouch! This reminded me of the mat burns I would get on the top of my feet while doing BJJ on the textured vinyl tatami mats.
What did I learn? To wear socks! (Which probably would have exposed me to ridicule and mangling in BJJ but which I can do in my garage with impunity.)