I see this constantly in engineers. My theory is that we're trained to see life as pass/fail and that starts to become a general theory of life. I found this guy to be quite helpful.

http://yourcharismacoach.com

He's got some great videos like how to warm up to conversations

https://www.youtube.com/watch?v=AtZUx6VLoY0

His stuff was so helpful to me I went to a seminar and then hired him and my social skills went through the roof. I got better clients (I run a consulting company), my marriage improved, and I just feel all the more outgoing despite a lifetime of being introverted.