The present study proposes that motives for working, and more specifically, the simultaneous experience of multiple work motives within an individual, have the potential to predict proactive behaviours at work. It examines this proposition among low-skilled workers, identifying their individual motivation profile based on forms motivational regulation within Self-Determination theory, and the subsequent proactive behavioural enactment of this motivation over time, operationalized as expansive and restrictive job crafting. First, it presents a new classification model for naturally-occurring motivation profiles, applying latent profile analysis to identify these profiles among 992 low-skilled workers and building on similar research within heterogeneous working populations. Four motivation profiles emerged from the population, including ‘core’ profiles evident in heterogeneous populations, and ‘peripheral’ or context-specific profiles. Second, a model of job crafting over time is presented, integrating Self-Determination theory, the Job Demands-Resource model, Conservation of Resources theory and Broaden-and-Build theory of positive emotion. Hypotheses from the temporal model of job crafting are tested using latent growth modelling over 4 waves. As hypothesized, at variable level, trajectories of expansive crafting were continuous, while those of restrictive crafting were non-continuous, and levels and trajectories of crafting varied significantly by motivation profile. Specific hypotheses regarding crafting by motivation profile were also largely supported. Findings revealed that the lowest levels of expansive crafting occur among Amotivation Dominant/Balanced Low profiles, and that as levels of expansive job crafting increase so too do levels of autonomous motivation in a given profile. In addition, continuous trajectories of expansive crafting only occur among individuals with a balance of autonomous and controlled motivation in their profiles (Balanced profiles), while restrictive job crafting is always non-continuous regardless of profile. Contributions to theory are discussed along with implications for practice and future research.