Essentially reading actively keeps you focused and helps locate important concepts quickly later on. Don Blohowiak, in his post Reading with Gusto, takes highlighting to another level by recommending that you indicate why the highlight was made, using the following notation:
R = Research this further
Q = Quote directly
T = Technique to integrate into the processes of my work or life
A = Action item to put on my To-do list related to work in progress...
Read selectively, by this I mean feel free to stop reading a book if it’s not adding value to your life, similarly skip chapters or paragraphs if they’re not relevant or resonating with you. Identify and focus on those chapters or paragraphs which will add the most value
...
extract and implement the key ideas from a book
http://www.thepracticeofleadership.net/2005/02/23/how-to-read-and-digest-a-book/