So these are the qualities you bring to the breath: mindfulness, keeping the breath in mind; alertness, being alert and sensitive to the breathing; and ardency, trying to make that sensitivity even more refined, more continuous.

"So these are the qualities you bring to the breath: mindfulness, keeping the breath in mind; alertness, being alert and sensitive to the breathing; and ardency, trying to make that sensitivity even more refined, more continuous. So, as we focus on the breath, it’s not that we’re just getting the breath. We’re also developing good qualities in the mind."

~ Thanissaro Bhikkhu "Making a Difference"