It is important to realize that there is a difference between mindfulness and concentration. Concentration is important. It helps you to focus your attention on one thing or another, and in this way it helps you to take command of what goes on in your mind. But mindfulness is another step beyond concentration. Mindfulness is a state of awareness. It is “presence” of mind.
Concentration is the tool you use to bring your mind into focus and to close the door on mental chatter, but it’s still up to you to “show up” and be present in the moment.