A quick reply to the least relevant paragraph...

> Anyway, I've been standing in one spot on a concrete floor for about four and a half hours straight, so my feet are pretty tired. I don't know how cashiers at WalMart do it all day every day.

They have special floormats that are very squishy to ease impacts with the floor and to allow more shifting of one's weight from side to side. The mats have sharply angled sides so that the feet can be placed at a variety of angles, and there is a small footrest above the mat so that a foot can be elevated. Plus, the cashiers get used to it after a few days.

Ga"did not learn this in biomedical engineering classes"be