Having put this into practice, I have experienced a deeper connection with everything I do. I've found it can be done with everything I do including cooking, dish-washing, painting, etc. This is a great practice in mindfulness. You become one with everything you are doing while realizing this, which Katagiri Roshi himself explains this topic in his book Each Moment is the Universe, and calls it "The great enlightenment."
This is also a great example of why Zen is considered "practice-realization." We don't have to wait for enlightenment, it happens all the time if we put into practice the teachings and see the world from what some call "Big Mind" or "Universal Mind."
I highly recommend practicing the "Mountains walk" frame of mind.