<p>Based on the multilevel Job Demands-Resources (JD-R) theory, job crafting as a proactive behavior, psychological capital (PsyCap) as a personal resource, and work engagement dynamically interact in the form of a daily gain cycle, reinforced by general levels of well-being. To explore these multilevel relationships, we conducted a daily diary study over two workweeks with a sample of 192 employees and 1,433 daily observations. Given the rise of hybrid work, we analyzed employees’ work location as an additional contextual factor. Multilevel analyses revealed positive and reciprocal relationships between daily levels of job crafting, PsyCap, and work engagement, supporting the proposed gain cycle. However, relationships varied by job crafting type. While seeking resources and seeking challenges showed positive reciprocal links with work engagement, reducing demands showed a negative reciprocal relationship. Furthermore, only seeking resources was positively and reciprocally related to PsyCap. We also found differential effects for office and remote workdays, suggesting that job crafting behaviors and their effectiveness depend on employees’ work location. While general well-being did not moderate the daily gain cycle but exerted direct effects, additional analyses revealed a moderating role of personality traits. Our findings highlight the importance of considering boundary conditions and differentiating between job crafting dimensions in future research on gain cycles. By explaining why the same proactive behaviors may be effective for some employees but not others, and on some days but not others, this study provides valuable guidance for interventions aimed at enhancing employee health and adaptability in hybrid work environments.</p>