Tangentially, if that callus was a plantar callus (circular with a painful point in the center), you can get sticky pads with salicylic acid from the drugstore that will gradually destroy it. Much safer than digging into your foot with a knife, but I'm glad to hear it worked for you!
giardini|1 month ago
Yes, I didn't know WTF was there but over the years it had grown beyond annoying , becoming so painful I couldn't tolerate it. I thought perhaps something (a splinter, piece of glass or steel, etc.) had become embedded in my foot. I was determined to dig it out. I'm tall and not flexible so I cannot easily see all of the bottom of my foot. But I can reach it.
The callus was surprisingly small (~1/2") and came out in one piece after about 10 minutes of work. Nothing embedded. No bleeding, just a lot of knife-wiggling. The bottom of the foot is really tough!