Introduction: The coronavirus disease (COVID) 2019 pandemic remains a great challenge for the healthcare system. The widely reported prolonged signs and symptoms resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (Long-COVID) require medical care. The aim of the study was to assess factors, including lifestyle variables, related to the course of COVID-19 infection and to assess their impact on prolonged symptoms in non-hospitalized patients with COVID-19. Methods: A total of 1,847 (637 men and 1,210 women) non-hospitalized participants of the STOP-COVID registry of the PoLoCOV-Study who, following the COVID-19, underwent check-up examinations at the cardiology outpatient clinic were included in the analysis. Results: The study participants (median age 51 [41–62] years) were evaluated at 13.4 (8.4–23.6) weeks following the diagnosis of COVID-19. Female sex (odds ratio [OR] 1.46 [95% CI 1.19–1.78]), body mass index (BMI; per 1 kg/m2: 1.02 [1.00–1.04]), hypertension (1.39 [1.07–1.81]), asthma (1.55 [1.06–2.27]), stress or overworking (1.54 [1.25–1.90]), and nightshift work (1.51 [1.06–2.14]) were independently related to the severity of symptoms during acute phase of the COVID-19 infection. The Long-COVID syndrome was independently related to the female sex (1.42 [1.13–1.79]), history of myocardial infarction (2.57 [1.04–6.32]), asthma (1.56 [1.01–2.41]), and severe course of the acute phase of the COVID-19 infection (2.27 [1.82–2.83]). Conclusion: Female sex, BMI, asthma, hypertension, nightshifts, and stress or overworking are significantly related to the severity of the acute phase of the COVID-19 infection, while female sex, asthma, history of myocardial infarction, and the severity of symptoms in the acute phase of COVID-19 are the predictors of Long-COVID in non-hospitalized patients. We did not find an independent relation between Long-COVID and the studied lifestyle factors.