The purpose of this study is to evaluate the effect of hardiness on the perceived military performance of reservists, i.e., young people who have full-time jobs in a civilian sector and perform military training as a part of their civic duty. We proposed the conceptual model with conditional indirect effects of the hardiness on personal military performance, where mediated moderation effects are observed from personality traits and variables important for military service: team cohesion, perceived stress, and psychological resilience. The final dataset was comprised of 384 self-reported paper–pencil questionnaires filled out by reserve soldiers, and PROCESS Macro 3.5 Model 7 and Model 14 were used for the analysis. The results revealed that perceived stress (Model 1) and psychological resilience (Model 2) have a statistically significant moderate mediating effect on the interlink between hardiness and performance when personality traits and team cohesion are taken into consideration. The change in R2is statistically significant and explains how perceived stress and psychological resilience affect individuals. When psychological hardiness is low, the level of perceived stress has a statistically significant moderating effect, i.e., it reduces the effect of hardiness on performance. When comparing the effects of perceived stress and psychological resilience, the latter has a stronger moderating effect on performance. Specifically, the moderating effect of resilience was more evident in Model 2 (66.9% variance, r = 0.818) for the military performance of the reservists than the perceived stress in Model 1 (52.5% variance, r = 0.724). This means that resilience increases the accountability of Model 2 compared to Model 1 by 14.4%. We conclude that resilience training could statistically significantly increase the military performance of reserve soldiers as a tactical population.