Degree Name

Doctor of Philosophy


Department of Psychology


Despite the increasing use of the term mental fitness, there are no consistent theoretical foundations, models or reliable and valid measures to use in research and practice. By using the adjective ‘mental’ prior to fitness, mental fitness can be seen as analogous to physical fitness. Physical fitness is a better known domain and it can be used to enable people to grasp potential meanings of mental fitness.

To commence the process of defining and measuring mental fitness, a conceptual review and two studies were conducted. The purpose of the conceptual review was to explore the historical, popular and scientific meaning and use of the term mental fitness and how it could be utilised within psychology. The review provided evidence to formulate an initial definition of mental fitness and a set of four guiding principles. Further, this review suggested an example of a resource index containing existing, published psychological theories and variables that are associated to positive mental health outcomes. This example resource index was proposed within a framework based on the physical fitness analogy of strength, endurance and flexibility. Following on from the conceptual review, a Delphi study was conducted to engage an international expert panel (n = 25) to evaluate the proposed definition and four guiding principles of mental fitness, expert consensus was achieved. Results provided an updated definition of mental fitness as being “the modifiable capacity to utilise resources and skills to flexibly adapt to challenges or advantages, enabling thriving”. Results for the four guiding principles were (1) fitness is a positive term without connotations of illness implied by mental health or mental illness; (2) mental fitness could be understood by the wider community in a similar way to physical fitness; (3) mental fitness is measurable; and (4) mental fitness can be improved, in a similar way to physical fitness. The panel also offered valuable, qualitative input and recommendations for future research and practice. The final study was conducted to provide preliminary empirical support for the concept and measurement of mental fitness. Exploratory (EFA) and confirmatory (CFA) factor analysis (n = 223) was used to analyse items from a selection of variables drawn from established measures. Results from the EFA identified four factors labelled strength, endurance, flexibility, and team supporting the item content and the physical fitness analogy. Results from the CFA provided preliminary evidence for a multifactorial model of mental fitness and validation for the four factors. Moreover, results provided initial validation for a mental fitness model containing the four factors subsumed by a second order factor of mental fitness. Limitations and future directions are discussed, as are the broader theoretical and empirical implications of the research. The preliminary findings suggest that the concept and model of mental fitness can provide a new and positive approach to the language and measurement of positive mental health aligned to the physical fitness analogy. This can create a broader understanding that, as in physical fitness, mental fitness requires the practice of intentional activities to create positive habits of mind that lead to higher levels of well-being, optimal functioning and quality of life outcomes.