Today’s job demands−resources (JD–R) literature emphasizes the interactions between job demands and resources. However, the dynamism of JD–R processes in which individuals manage to counteract the detrimental effects of job demands on employees by flexibly adjusting resources calls this relationship into question. Hence, in this study, we depict JD–R dynamics in the workplace by developing a cross-level moderated-mediation model that unveils the different roles played by job and personal resources when they are woven together with job demands. We examine how and when the relationships among three types of resources—organizationally assigned high-performance work systems (HPWSs), psychological capital (PsyCap), and social support climate (SSC)—help employees deal with excessive workload and unhealthy emotional demands. Using a two-wave research design, we measured and tested the causal relationships of the proposed variables. We found that (1) HPWSs had a negative effect on workload, (2) workload provoked employee emotional demands, (3) the interaction between HPWSs and PsyCap increased workload, and (4) SSC mitigated the positive effect of workload on employee emotional demands. This study contributes to the JD–R theory and literature by unlocking the potential roles of various resources. Theoretical and practical implications, limitations, and future research avenues are also presented.