How did the cards Kay received from patients keep him positive as noted in the nonfiction book, This Is Going to Hurt?

As Kay tells the reader, despite the lack of praise given to doctors by the institution itself, "patients tended to get it, though" (89). He describes the cards he receives the "little fist bumps that kept me going" (89). Ultimately, cards play an important literal role in Kay's life as a doctor while simultaneously acting as symbols for his theme of appreciation.