PURPOSE: Post-COVID fatigue significantly limits recovery and return-to-work in COVID-19 survivors. We aimed to assess the effects of physical exercising on post-COVID-19-symptoms, physical/mental capacities and workability within a workplace-health-promotion project in health-care personnel. MATERIALS AND METHODS: Thirty-two HCWs were enrolled in two groups based on Post-COVID-Functional Scale (PCFS) scores: (1) severe (SSG,  = 11) and (2) mild (MSG,  = 21) symptoms. The participants underwent an eight week exercise intervention program consisting of two supervised resistance exercise sessions per week plus individual aerobic exercise recommendations. Primary outcome-parameter for physical fitness was VOpeak. Further, physical function (6MWT, 30 s sit-to-stand test (30secSTS)), mental health (anxiety (GAD-7), depression (PHQ-9), stress (PSS-10), fatigue (BFI), resilience (BRS)), cognitive capacity (MoCA) and workability (WAI) were assessed at baseline, after 4 weeks and after completion of exercise intervention. RESULTS: VOpeak improved significantly in the SSG by 2.4 ml/kg/min (95% CI [1.48; 3.01], adj. < 0.001) and non-significantly in the MSG by 1.27 ml/kg/min (adj. = 0.096). Both groups significantly improved their 30secSTS ( = 0.0236) and 6MWT ( = 0.0252) outcomes in both follow-ups (4 weeks and 8 weeks after inclusion). The SSG improved more than the MSG in VOpeak and 6MWT both after 4 and 8 weeks, respectively, although not statistically significant; findings were vice versa for the 30secSTS. 30secSTS outcomes correlated significantly with mental health outcomes and workability. CONCLUSIONS: Post-COVID exercise intervention improved physical fitness, psychological outcomes and workability in HCWs. Cases with severe fatigue showed higher benefit levels compared to those with mild symptoms. The safe and highly feasible 30secSTS correlated well with physical and mental outcomes and better workability in COVID-19 survivors.Implications for rehabilitationPhysical exercising showed to be an effective intervention method in the rehabilitation of COVID-19 survivors suffering from post-COVID syndrome by positively affecting both physical and mental health.In health care workers suffering from post-COVID syndrome, increases in physical performance are directly related to improvements in work ability.The 30 s sit-to-stand test (30secSTS) showed promising results as clinical assessment tool.The results of this study indicate that physical exercising will need to play a large and substantial role over the next years in the rehabilitation of COVID-19 survivors suffering from post-COVID-19-syndrome as it positively affects both physical and mental dimensions of the post-COVID-19-syndrome as well as work ability.