Teachers are experts of their content. You're an expert reader or writer, mathematician or historian, scientist or musician. More likely than not, you teach what you teach because you love it, you're passionate about it, and you'd love to pass that fascination on to your students.
If you teach science, chances are, thinking like a scientist, comes much more naturally to you than it does for me. Or for your students. The same is true for all content areas (ELA included!). The way a scientist reads an article about genetics is different than the way you read a novel to prepare for a book club, and it's different than the way a historian reads a primary source.
The challenge for experts is to realize the thinking they are doing, even though it is second nature to them. As teachers, we must first notice our thinking processes when we are accessing text so that we can turn our THINKING into TEACHING.
Too often we just assign a task to students or we show them an exemplar. The problem with only showing an exemplar is that it doesn't show the PROCESS. Without showing the process we can unintentionally give students the impression that their work should automatically be the quality of the exemplar, without the puzzling, struggling, revising, etc.
Modeling is different than assigning. Thinking aloud is different than telling. Modeling and thinking aloud turn your thinking into teaching and make the process accessible for students. And isn't the process really what it's all about? The process is what will enable them to continue to become passionate and fascinated by your subject area, long after they leave your classroom.