Job crafting refers to the proactive actions employees take to redesign their jobs in order to get a better fit with their competencies, expectations, and wishes. So far, little is known about job crafting's underlying mechanisms. In this study, we examine how two different states of affective well-being (workaholism and work engagement) relate to job crafting 3 months later and how these well-being states steer different self-management behaviours, which ultimately lead to job crafting. Structural equation modelling on a heterogeneous sample (N = 287) revealed that work engagement and workaholism both relate to expansive job crafting through different self-management strategies. Work engagement relates to challenge and resource seeking via self-goal setting and self-observation strategies, whereas workaholism associates with challenge and resource seeking only through self-goal setting. In addition, the results show a strong relationship between workaholism and self-punishment. Altogether, the findings suggest that self-management strategies can function as an explanatory mechanism for different job crafting behaviours.