The aim of the present pilot study was to assess the effect of a brief work-related self-affirming implementation intention (WS-AII) on the well-being of primary school teachers. Participants were randomly allocated to one of two conditions: one in which they were asked to create a WS-AII or one in which they were asked to create a control implementation intention (C-II). State anxiety was measured pre- and post-manipulation, self-efficacy at post-manipulation only, and emotions in teaching and emotion regulation at baseline and at a two-week follow-up. There were statistically significant differences between the WS-AII condition and the control. Teachers who created work-related self-affirming implementation intentions reported an immediate reduction in state anxiety. Positive effects extended over the two-week period, with teachers in the WS-AII condition also reporting more positive emotions in teaching and the use of reappraisal emotion regulation strategies rather than emotion suppression. Results suggest that the integration of the WS-AII into existing organisational practice may be of benefit to the well-being of teachers and other highly stressed workers.