Growing up, we were told to "sit up straight" -- not because it's better for our health, but because it looks more productive. As it turns out, sitting up straight (i.e. 90-degree angle at the pelvis) is actually harmful in the long run. We've known this for a while -- since 2006, actually -- but people keep perpetuating bad facts. Isn't it time to put these myths to an end? Stop sitting up straig