the exercise is amazing , and if you allow it changes your life.
i discovered a great book " the five tibetans" by chris s. kilham years ago on the way to india.
i practiced breathing at first, than added the exercise itself. it became more dynamic and powerful (if you believe in it)
you feel so energized for a whole day, so you can share it with others:-)
it helped me a lot a fresh air in Dharamsala (Himachal Pradesh) during beginning.
later i found that there are other great meditation techniques in the book, which make it unique/rare from plenty of other books with the same name "the five tibetans". it´s a true jewel of my library.
i´m grateful that mr.kilham decided to share ancient secret techniques with the rest of us. https://www.amazon.com/Five-Tibetans-Dynamic-Exercises-Personal/dp/1594774447
best of luck!