Shyness may hinder a career change to the extent that social contacts are avoided. Yet even shy people can learn how to expand their circle of acquaintances and use techniques similar to networking and exploring the hidden job market.
In humans, shyness is a feeling of insecurity or awkwardness that certain people experience while being among others, talking with others, asking favors of others, etc. In zoology, shy generally means "tends to avoid human beings"; see cryptic.