Evolve/Adapt yourself to any conditions

Ok, this idea came to me recently when i was talking to my friend about her schooling for nursing. She was saying how whenever you get an injury it heals itself and adds a little bit more protection to that area. A prime example would be, callouses on your hands. You use your hands alot, they become calloused, because they need the extra protection since you use them so much. So it brings me to wonder, could we condition our bodies to take change to something else? I've heard of guys punching cinder blocks and so much their knuckles become extra hard, which is what lets them punch threw this stuff. Was curious as to if it was possible to condition yourself to live in extreme conditions if you endured small amounts at first then gradually more.