From the chapter "What Is Mindfulness?" in Wherever You Go, There You Are by Jon Kabat-Zinn:

Mindfulness has been called the heart of Buddhist meditation. Fundamentally, mindfulness is a simple concept. Its power lies in its practice and its applications. Mindfulness means paying attention in a particular way: on purpose, in the present moment, and nonjudgmentally. This kind of attention nurtures greater awareness, clarity, and acceptance of present-moment reality. It wakes us up to the fact that our lives unfold only in moments. If we are not fully present for many of those moments, we may not only miss what is most valuable in our lives but also fail to realize the richness and the depth of our possibilities for growth and transformation.

^z - 2008-11-05