It's a bit like focusing on the present moment and adjusting to the pace. When I find that middle I don't think about the past or the future, I just do whatever I do; a series of muscular contractions I've had since a neck injury dissipates and the general state improves.
It's probably an occurence many are aware of, but it's my recent thing.
It reminds me of a large inscription on a wall in Berlin that reads: "How Long is Now."
Another, more vulgar, there reads: "Free your mind and your ass will follow," but I think they both mean the same thing.