Grab your favorite book or a magazine. Prepare your surroundings and yourself for reading.
Now you will start from begging of a chapter or article and finish it. Now read it as fast as you can using your favorite technique. Close the book (magazine). Now try to recall the information that you have read. Calculate your time and aprox. your ability to recall the information. Relax now, exercise if you want ease that back pain. Walk for a couple of minutes, you can go outside for a quick walk if you want. Now go back to the same thing and read the same and the next one.
Try to experiment as much as possible with techniques in order to see what suits you the best.