How do corns develop on your feet and calluses on your hands formed?

Lotion or surgery. . Corns and calluses occur because of pressure points. Surgery can fix this, but if you're not ready for that, trimming them down and regular use of lotion may soften them to the point they don't bother you. You can also try larger shoes that don't rub against the painful areas! offloading orthotics can also help: see your podiatrist for casting.
Friction/pressure. Friction or incresed pressure applied to a specific area can cause this. Some deformities of feet or hands can make one more prone to this.