I have been silent because I have been painting... and painting... and painting. And it hurts. I have been painting for so many hours at a time - one day for maybe 15 hours with maybe a couple of short breaks, that I have developed a very bad shoulder pain. This is in addition to the fact that I sprained my ankle - tore two ligaments, bone contusions, blah blah (this was is a running injury, not painting). So sitting in one place at the stool is painful for the foot and ankle. But now with the shoulder and arm pain, well, geez! This seems to be some sort of nerve impingement because the pain is traveling down my arm when I keep my arm out for too long. Agony. I think if you ask any illustrator if they start to get pains like this they'll probably tell you about some. And most people who don't have to sit for long, long stretches at a time in odd positions probably wouldn't think about this.
Well now when you look at a nice children's book: think about THE PAIN!!!