I notice from other posts that you have extensive background in this. I'm curious -- my sister-in-law is seriously considering changing the focus of her career. She's done administrative work for quite a long time but has gotten worn out on the field (entertainment). She is considering changing to the medical field, and is interested in perhaps medical billing. What type and length of study and training is required for someone who is serious about pursuing this on a full-time basis? Is the field very crowded? Is the work itself stressful? Or is that dependent on the location? She is a very committed individual, so I have no doubt that if she were to pursue this, she would do her best. Thanks for any direction or caveats you can provide.