In my classes, and as a Transformation Facilitator, I avoid using the term "mindfulness" to describe having energetic awareness. Being energetically aware means that you know when your heart is transmitting love/joy/gratitude electromagnetic frequencies, and when it is transmitting fear frequencies. (This is discussed and illustrated in great detail in my book, Spiritual Transformation Simplified™) The heart is the transmission center, not the brain, as proven by the Institute of HeartMath, to cite one research organization. Therefore, I avoid using "mindfulness", as it tends to cause us to "think" about our state of being, shifting focus to the brain/thoughts. This only serves to further activate the self-perpetuating loop of fear-dominated frequency transmission. By focusing on the heart, and being aware of what frequency is dominating our heart transmission, with the proper tools, we have the ability to quickly shift our heart transmission out of fear back into the frequency of love/joy/gratitude.
There are clear physical clues to insure clarity on your current state of frequency transmission. If the center of your chest feels heavy, contracted, tight, as if there were a chunk of lead in there...then your heart is in the fear dominant transmission mode. Conversely, if the center of your chest feels expanded, warm, light...then love/joy/gratitude is the predominant transmission. I invite you to play with this, have fun, practice being aware of your heart transmissions.
In Light and Gratitude!