Mindfulness is full awareness of our thoughts, feelings and actions in each moment.  It is the full presence and awareness of our experience.

Mindfulness can be compared to self-awareness. You are aware of self.  Being in a mindful state can also be further defined as being in a state of self-awareness without judgment.  Consciously observing without judgment is what I like to describe as passive observation. 

When you are mindful, you are completely self-aware, in the moment and in a state of non-judgment.  You are just accepting and experiencing the moment.  Being mindful (self-aware and passively observing) during meditation, will slowly bring this awareness into your daily routine.

"The Buddha advocated that one should establish mindfulness (satipatthana) in one's day-to-day life maintaining as much as possible a calm awareness of one's bodily functions, sensations (feelings), objects of consciousness (thoughts and perceptions), and consciousness itself." (Source Wikipedia: Mindfulness).

As long as we have practiced neither concentration nor mindfulness, the ego takes itself for granted and remains its usual normal size, as big as the people around one will allow.

Ayya Khema