Mindfulness refers to paying attention in a particular way, in the present moment without exercising any judgment. The most famous exponent is Kabat-Zinn Mindfulness, who then founded the stress reduction program based on Mindfulness at the University of Massachusetts.
Mindfulness is paying attention on purpose. It involves a conscious direction of consciousness, but note that full attention and consciousness are not the same, such is not the same eating, eating mindfully. When you eat consciously, is aware of the process of eating. Sensations and body responses to them are noted, and if the mind wanders, instantly try to focus again.
However, when eaten traditionally, one is aware of the act yet you are thinking about a thousand other things as well can be watching TV, reading or chatting with another person.
Therefore, a very small part of the consciousness is absorbed with food and therefore is hardly aware of physical sensations, least of thoughts and emotions.
The intent is an important part of mindfulness. According to the example, would be a conscious attempt to bring attention back to the food, have a goal. Pay attention to the present moment.
When the mind wanders, do it for all kinds of thoughts, including those expressing anger, desire, depression, revenge, self-pity, etc. As we give ourselves over to these thoughts, these emotions are reinforced and cause suffering.
The Mindfulness emphasizes that the past no longer exists, and the future is just a fantasy until it happens. The only time you can really experience, is the present moment , but paradoxically currently seems the most try to avoid.
In mindfulness meditation what is important is what arises in the present moment. And when thoughts about the past or the future take us away from our present experience, it seeks to distance and simply return to now.
By directing awareness to take away from such thoughts on purpose and focus on the present experience, the effect they can have on our lives is decreased, and an area of freedom, where calm and joy can grow is created.
Finally, pay attention without judging is just accept everything that comes and observe mindfully, thus we realize that what happens happens through us, and ceases to exist. Whether a pleasant experience or a painful experience in Mindfulness is treated the same way.
Cognitively, the Mindfulness is aware that some experiences are pleasant and some not, but on an emotional level simply does not react, this is called equanimity, stillness and balance of mind.