It's much like standing up like an adult instead of slouching. Much of the time having flat feet and collapsed arches is simply that people are unaware of the fact that maintaining those arches can take a little bit of thought and effort. Usually high priced orthotics and different shoes are a waste of time and money. Being aware of it and spending some time out of shoes can fix that right up.
Now I'm not saying that you should be squatting in chucks, I'm talking about walking and every day normal activity.