As a business owner, I have somewhat of a shy personality. However, I love what I do and that is what I used to overcome that side of my personality. It's absolutely difficult to cold call a potential client, but if that's the business you've chosen, there is no way around it. Perhaps sales isn't your calling. Have you thought about account management or maybe something more administrative? If your introversion is this much of an issue, it seems independent consulting would only fan the flames for you. Going out on your takes, even more, pounding the pavement and getting in front of people.