If you are reading in order to become a better reader, you cannot read just any book or article. You will not improve as a reader if all you read are books that are well within your capacity. You must tackle books that are beyond you, or, as we have said, books that are over your head. Only books of that sort will make you stretch your mind. And unless you stretch, you will not learn.
How to Read a Book: The Classic Guide to Intelligent Reading (ed. Simon and Schuster, 2014) - ISBN: 9781476790152