So I've been asked to help out a few kids in my area that are wanting to get into the military. I've got a year to do this (they have a year of highschool left). Been doing lots of different things and the biggest hangup so far is quite frankly their feet/shins have no durability at all. If there shins start to feel it we stop whatever it is. Point me in the direction of how to think about conditioning feet/shins to be able to do what if they hadn't been playing video games the last decade wouldn't need thinking about?