Here is an article from the American Podiatric Medical Association's Website about working in a stand-up environment and the pain it can cause to your feet:

Friendly Footwear a Must for Those Who Work Standing Up

October 7, 2009 Bethesda, MD

The average American’s foot pain often gets in the way of daily activities. Perhaps no group suffers from chronic foot pain more than those who are constantly on their feet. According to the American Podiatric Medical Association's (APMA) 2009 foot ailments survey, 44 percent of respondents said they spend at least four hours standing every day. Additionally, nearly 78 percent of Americans have experienced foot problems as a result of wearing uncomfortable or ill-fitting shoes.
"The excess strain put on the legs and feet of those standing for long periods of time can take a massive toll on the body—especially for those working in the health care community," said APMA President Ronald Jensen, DPM. "Without the proper footwear that provides necessary support to the ligaments and joints of the feet, these individuals are subject to a host of ailments that can lead to chronic problems such as metatarsalgia—a pain and inflammation in the ball of the foot.”
Excessive standing and walking on hard surfaces like concrete can also increase the incidence of foot problems. However, many footwear companies create products that are specifically made for those who “work standing up.”

If you work in such an environment, you should keep an eye out for footwear which has been granted APMA’s Seal of Acceptance. The Seal of Acceptance Program recognizes products which have been found beneficial to foot health and of significant value when used in a consistently applied program of daily foot care and regular professional treatment.