I wrote an article on that topic for my blog.
http://www.phoenixquest.com.au/alexk/2008/04/16/purpose2/When you can say how or why doing (or reading) what you are, will lead you to a desired outcome or destination.
I'm doing / reading this, to attain [insert expected outcome. e.g build strength, acquire understanding about...] so I can... [ what is it you hope do with the gain from your investment of time?]
So I can...
That's how you recognise that you've just stated a purpose.
What helps you fill in the
So I can is your imagination. How do you see, feel or hear yourself using the information that you gathered from the book?
Example I'm going to finish the PhotoReading course so I can get through all my future reading requirements much more effectively. Add a little imagination and you can perhaps see yourself finishing text in record time and enjoying more free time with the family, you might feel the relief that comes with knowing that you finished your work during the work hours instead of having to take it home. You might even hear yourself talking about the new knowledge you got from the course of study you had undertaken.
AlexK