I came across this definition of mindfulness when listening to my audio book, Rising Strong by Brene Brown (side note: if you do not know Brene Brown, I highly recommend reading any of her books or listening to her Ted Talk on vulnerability. She's amazing). I thought I'd share the quote here. It comes from the Greater Good Science Center at UC Berkeley.
"Mindfulness means maintaining a moment-by-moment awareness of our thoughts, feelings, bodily sensations, and surrounding environment. Mindfulness also involves acceptance, meaning that we pay attention to our thoughts and feelings without judging them—without believing, for instance, that there’s a “right” or “wrong” way to think or feel in a given moment. When we practice mindfulness, our thoughts tune in to what we’re sensing in the present moment rather than rehashing the past or imagining the future.”