Simply put, mindfulness is moment-to-moment non-judgmental awareness.
There is just this moment. We are not trying to improve or to get anywhere else.
In any given moment we are either practicing mindfulness, or defacto, we are practicing mindlessness.
Practice moment to moment non-judgemental awareness.
Stillness, insight, and wisdom arise only when we can settle into being complete in this moment, without having to seek or hold on to or reject anything.