I had the opportunity to go to Medellin, Colombia and open a Call Center there a few years ago and one of the many things I was tasked with was recruiting and training the sales staff. One of the most effective things that I found that boosted their sales was also one of the simplest; standing up. When you sit down, it relaxes your diaphragm and when you stand while talking, it tends to give a person a more intense tone which helps to create a sense of urgency. You never see stockbrokers on the floor of the NY Stock Exchange sitting down for a reason. Something to think about and perhaps give it a try.