system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: why do shoes disintegrate when left unworn (for extended period of time) and frequently wearing them actually prevents/delays disintegration?
gpt
I am assuming you are talking about leather shoes. 

The leather is a natural product, with time the atmosphere dries the leather out slowly (imagine like a piece of bread left on a counter top). The loss of moisture hardens the leather. When you use the shoes, you sweat into the them, this replaces some of the moisture,  this is also why you should be polishing your shoes regularly. The polish helps to protect the leather with wax and other products to keep it in a good condition and supple.