Hockey’s motivation control theory of fatigue is formalised and explored in this system dynamics model to investigate fatigue development and ways to cope with it. The model reproduces the three work management modes proposed in the theory: engaged, disengaged and strain. These simulation results support the internal validity of the theory and build confidence in the model. Further simulation results extend the theory and reveal two additional, distinct behavioural patterns, that capture two more strain work management modes: sustained proactive coping and oscillations between proactive to reactive coping.The model has been developed for Yekatherina's PhD, which can be found through UCL library: Bobrova, Y. (2020) The adoption process of low-carbon home retrofit among UK homeowners: A socio-technical perspective and system dynamics model. PhD Thesis. University College London.The model has also been presented at the 2019 UK System Dynamics conference, for which Yekatherina received the Student Prize Award for the best student paper of the year: Bobrova, Y. and Papachristos, G. (2019) ‘Work management under stress: A dynamic exploration of a motivation control theory of fatigue’. Student Prize Award for the best student paper of the year. In: UK Chapter of the System Dynamics Society. Annual Conference 2019. 4–5 April. London, UK. Available at: http://systemdynamics.org.uk/wp-content/uploads/2019AC-Day2-Bobrova-Rep.pdf