This is the book that made meditation possible for me.
.. I suggest that you just try it for fifteen minutes in order to get a sense of what this work feels like. You start by placing yourself in a comfortable position so that you will get as few distracting signals from your body as possible..
..Now simply count silently each time you breathe out. Count “one” for the first breath, “two” for the second, “three” for the third, “four” for the fourth and then start with “one” again. Keep repeating this procedure until the fifteen minutes are up. The goal is to be doing simply that and nothing more. If other thoughts come in (and they will), simply accept the fact that you are straying from the instructions and bring yourself gently and firmly back to the counting. No matter what other thoughts, feelings or perceptions come during the fifteen minutes, your task is simply to keep counting your breaths, so keep trying to be doing only that. Doing or being conscious of anything else during this period is wandering away from the task.. Do
not expect to do well at it, to be able to succeed for more than a couple of seconds at a time in being aware only of your counting. That takes long practice. Simply do your best.
These excerpts from (just) chapter 2 of this book, and I was hooked. I have read and re-read this book, quoted from this book and used exercises with clients and subjects over and over. Therefore, I highly recommend this book (published in 1974, Bantam). Find it on ebay where it is reasonably priced.