The Way of Mindfulness in Buddhism, of deliberately being conscious of each physical action quite apart from the action itself, produces a different state from that of the ordinary person who may outwardly perform the same action. It develops concentration and an awareness which ultimately leads to the awareness of the being himself who practises the exercise. The ordinary person is lost in the action itself, in the thought itself, in the speech itself, and has no separate awareness of them. Practice of mindfulness gives a conscious responsibility for what is being done, what is being thought, and what is being said quite apart from what is observed and heard. It lights him up from within with intense concentration. This is a mental discipline practised daily by the Buddhist monks and useful to other seekers.
-- Notebooks Category 4: Elementary Meditation > Chapter 7 : Mindfulness, Mental Quiet > # 8