A Yichud With Every Breath
The Divrei Chaim of Sanz said of the holy Rizhiner that he could not draw even a single breath without making a yichud Hashem. The Rizhiner himself testified that his mind and thoughts were so firmly bound to Hashem that if he were alone on a desert island with no seforim, he would still not forget Hashem for even a single moment.
Source: Ner Yisroel IV, p. 144; Shevet MiYisroel, vol. I, p. 5