Here is an excerpt from Jack Kornfield’s book The Wise Heart which very clearly describes the gradual steps of the practice of mindfulness :
(My teacher) taught me to relax and feel my breath carefully, which helped quiet and focus my mind. Then he taught me just to mindfully notice the stream of thoughts and sensations without reacting to them as a problem. This took some practice.
Finally he taught me the most important lesson, to rest in consciousness itself. As his own teacher explains :
« We can notice the difference between consciousness and all the transient states and experiences that arise and pass away within it. When we do not understand this point, we take each of the passing states to be real. But when the changing conditions such as happiness and unhappiness are seen for what they are, we find the way to peace. If you can rest in the knowing, the pure consciousness, there is not much more to do. »
Jack Kornfield, The Wise Heart