Concentration is a cornerstone of mindfulness practice. Your mindfulness will only be as robust as the capacity of your mind to be calm and stable. Without calmness, the mirror of mindfulness will have an agitated and choppy surface and will not be able to reflect things with any accuracy.
Jon Kabat-Zinn (2005). “Wherever You Go, There You Are: Mindfulness Meditation in Everyday Life”, Hyperion
