I've tried to write a post on this concept and how it holds actors back several times over the past year, but once again, Bonnie Gillespie hits the nail on the head in a way better way than I ever could.
Go read ya'll.
And then set aside some time to wade through the archives - she's one of the best resources out there for an on-camera actor.
And Bay Area folks - have you taken a look at Apple Box Studios Films yet? A new by artists for artists company with a video creation focus - they shoot auditions, edit reels, and put together websites - I haven't had a chance to take advantage of their services yet, but I'm sure I will soon!