COVID-19 has forced universities around the world to suspend in-person teaching and adopt emergency remote teaching (ERT). To compensate for the suspension of in-person teaching, many universities mandated that teachers utilise video-conferencing software (VCS) to deliver synchronous online lessons conducted through VCS. This study explored the impact of ERT and the requirement to teach synchronously online through VCS on the motivation of university teachers at a major university in Hong Kong. In-depth interviews were conducted with nine teachers who had completed a full semester of ERT. The findings suggest that the teachers fell into two distinct groups. Teachers in one group (n = 5) seemed to thrive, reporting mainly positive effects of ERT on their motivation, while the others (n = 4) seemed to be just surviving, reported mainly negative effects. For members of the "thriving" group, the semester reinvigorated their teaching and provided them with new skills; members of the "surviving" group, by contrast, questioned their ability to teach, found it hard to build a rapport with learners, felt isolated, and struggled to find job satisfaction. The study concludes with a discussion of measures that could help university teachers to maintain their motivation during online instruction.