There’s a brief description of this exercise here.
I realized the other day that I’d accidentally created a kind of “check” on my day, both at the beginning and at the end. In the morning, my ten-minute mindfulness meditation is one of the first things I do, and how easily that works for me is a good indicator of my mental state. In the evening I practice viola, and that seems to similarly hinge on my mental state.
I think I would also benefit from a midday mindfulness session (although realistically it’s unlikely to happen on a regular basis). I noticed while doing this meditation that I began to develop a sense of how my day had been trending since the morning; the various small stresses and negative thoughts of the day came into clear focus. It seemed to help me nudge myself toward a better place.
And that, after all, is the point of these exercises.