By asking the question, you step out of habitual responses for that moment - out of the light trance in which we all spend a good deal of time.
Why not answer the question? Because you ask the question only in order to come out of that light trance. If you need to change the quality you are bringing to the moment you will realise this instantly, in my experience, and will alter your approach without needing to analyse.
By the way, when I say 'this moment' I'm really saying 'the experience that I am having right now.' So a longer version of the question would be "What quality am I bringing to the experience I'm having right now?"
One could say the question is another way of saying 'Wake up!' And mindfulness practice aims to keep us awake to our experience and to what we are adding to it.
So the question, "What quality am I bringing to this moment?" can bring us straight into the heart of mindfulness practice.