If you had to carry your loaded 20 pound bug out bag and get the heck out of Dodge on foot, how would you fare? What if you had to carry your sleeping child over the mountains in order to evacuate?
If the proverbial S hits the F, we will see a lot of serious injuries, and even deaths, from people making unaccustomed physical demands on their bodies. A lot of us are going to be using muscles we forgot we had. Our bodies will be under enormous cardiovascular stress. On top of the mental stress we will undergo, the physical stress will very likely kick our butts.
Prepping with food and medical supplies is not enough. A good mental attitude is not sufficient. We have to prep our bodies too.