Deeper, conscious breathing opened my chest, relaxed my mind, and led to my finding it perfectly possible to remain still and at peace for fifteen minutes afterwards without feeling compelled to "get on with something else" or falling asleep. The suggestion that it's OK sometimes just to imagine doing some of the movements removed anxiety about keeping up with the pace, or misunderstanding what's being suggested. (Sometimes concentrating on one movement means missing the counsel concerning the next.) Really helpful for someone like me with only a little direct experience of yoga thus far. I hope to go deeper. Many thanks.