Mindfulness is a technique in which a person becomes intentionally aware of their thoughts and actions in the present moment, non-judgmentally. It plays a central role in Buddhism, with Right Mindfulness being the seventh element of the Noble Eightfold Path, the sadhana of which is held in the tradition to engender 'insight' and 'wisdom' .
Right mindfulness involves bringing one's awareness back into the present moment. By residing more frequently in the present moment, practitioners begin to see both inner and outer aspects of reality. Inner reality may unfold as one sees that the mind is continually chattering with commentary or judgment. By noticing that the mind is continually making commentary, one has the ability to carefully notice those thoughts, and then decide if those thoughts have value. Those practicing mindfulness realize that "thoughts are just thoughts"; the thoughts themselves have little or no weight. One is free to release a thought ("let it go") when one realizes that the thought may not be concrete reality or absolute truth. Thus, one is free to observe life without getting caught in the commentary. Many "voices" or messages may speak to one within the "vocal" mind. It is important to be aware that the messages one hears during "thinking" may not be accurate or helpful, but rather may be translations of, or departures from truth.
Mindfulness points to: Being aware of and paying attention to the moment in which we find ourselves. Our past is gone, our future is not yet here. So what exist between them is the present moment. If I can observe and not get caught up in my thoughts, it is all that I have. The here and now, the present is the link which holds what was and what will be. My past was a series of present moments which brought me to this present moment. My future should it happen will be a series of present moments effected by only present moment in which I am now living, being, doing, observing, being aware or unaware, and attentive or unattentive.
However, mindfulness does not have to be constrained to a formal meditation session. Mindfulness is an activity that can be done at any time; it does not require sitting, or even focusing on the breath, but rather is done by bringing the mind to focus on what is happening in the present moment, while simply noticing the mind's usual "commentary". One can be mindful of the sensations in one's feet while walking, of the sound of the wind in the trees, or the feeling of soapy water while doing dishes. One can also be mindful of the mind's commentary: "I wish I didn't have to walk any further, I like the sound of the leaves rustling, I wish washing dishes wasn't so boring and the soap wasn't drying out my skin", etc. Once we have noticed the mind's running commentary, we have the freedom to release those judgments: "washing dishes: boring" may become "The warm water is in unison with the detergent and is currently washing away the plates grime, the sun is shining through the window and casting an ever greater shadow on the dish's white ceramics.". In this example, one may see that washing does not have to be judged "boring"; washing dishes is only a process of coordinating dishes with soap and water. Any activity done mindfully is a form of meditation, and mindfulness is possible practically all the time.
As one more closely observes inner reality, one finds that happiness is not exclusively a quality brought about by a change in outer circumstances, but rather by realizing happiness often starts with loosening and releasing attachment to thoughts, pre-dispositions, and "scripts"; thereby releasing "automatic" reactions toward pleasant and unpleasant situations or feelings.