Purpose The purpose of this analysis was to explore associations between exercise behaviour among breast cancer survivors and three behavioural constructs from distinct theories: self-efficacy from social cognitive theory, motivation from self-determination theory, and habits from habit theory.

Methods Breast cancer survivors (n = 204) completed a cross-sectional survey that collected demographic and disease characteristics, exercise levels, and self-efficacy, motivation, and habits. Multivariable linear regression models were used to identify constructs associated with total activity and resistance training.

Results Participants were a mean (SD) age of 57.3 (10.8) years and most were diagnosed with early-stage disease (72%) and engaged in sufficient levels of total activity (94%), though only 45% completed ≥ 2 resistance training sessions/week. Identified motivation (ꞵ[95% CI] = 7.6 [3.9–11.3]) and habits (ꞵ[95% CI] = 4.4 [1.4–7.4]) were significantly associated with total activity (as were body mass index and disease stage), whilst identified motivation (ꞵ[95% CI] = 0.6 [0.3–0.9]) and coping self-efficacy (ꞵ[95% CI] = 0.02 [< 0.01–0.03]) were significantly associated with resistance training. The models explained 27% and 16% of variance in total activity and resistance training behaviour, respectively.

Conclusion Results suggest that incorporating strategies that support identified motivation, habits, and coping self-efficacy in future interventions could promote increased exercise behaviour among breast cancer populations. Future longitudinal research should examine associations with exercise in a more representative, population-based sample.