Humans aren't nearly as robust as ponies. Simple gestures such as hugs, pats on the back, and hoof bumps are all well and fine when it's another pony on the receiving end. With a creature a fraction of their mass, ponies often forget how fragile others can be.
A man reflects on his fragility during a routine checkup, and realizes that he might not be the only one affected by simple actions one might take for granted.
An audio reading has been done by the illustrious Illya Leonov.