I worked at a job where you just do not do that. I was constantly being told to "walk with a purpose" and such. I think because of this I learned to walk head high, chest out, hands OUT of pockets. I have special sympathy for people who receive this criticism and so I try not to do it myself to others, but I must admit those bodily expressions are typically seen as signs of self-confidence and it feels good to be interpreted that way so I continue the behavior. I don't think of it as inherently being correlated, but for me it is a way of communicating how I see myself to people who do see it that way.