When we observe the process of breathing, really observe it, even for a moment, a very profound meditation happens. I recently received a newsletter from the Advaita Fellowship (Wayne Liquorman), and am quoting from it below, as it is such a beautiful understanding of the gifts that observing the breath can bring.
"This aliveness we are talking about is worth investigating. It is here, in this moment. It is as close to you as your breath. In fact, your breath IS this Livingness. You do not have to remember to breathe. Your breath is literally breathing you. Stop reading the words on this page for a moment and investigate this phenomenon of breathing....
(If you did not stop, but simply read on to this sentence, I fully understand...you are a lot like me....however there REALLY is something to be seen in the stopping for a moment even if you are an "advanced" student and have examined your breath many times previously.)
Perhaps you were able to see the way in which your breath "just happens." You breathe even when you forget to breathe. There is a force here that operates independent of your decisions and intentions... It is this Life that is living you even to the extent that you falsely believe yourself to be living IT."