As the common saying goes: “if you do not use it- you will lose it”. The same sense applies in all the ways that you’ve distanced your body from nature. If you do not expose yourself to perceivably life-threatening situations, then your body loses its ability to process stress productively. If you do not expose yourself to the cold, your body loses its ability to rapidly generate heat. And if you do not expose your body to hunger, then it loses the ability to process your fat storage into energy. Thus, chronic anxiety, poor immune health, and obesity plague first-world economies.