To contain the COVID-19 pandemic, public health actions have changed the everyday life with an inevitable impact on individuals and their social life. We conducted a German online survey from April until August 2020 investigating health-related, social, behavioral, and psychological effects of the COVID-19 pandemic. We explored effects on mental health by (a) clustering participants in two clusters and (b) analyzing the clusters using correlations and regression models. Participants belonged either to a cluster characterized by higher general well-being or to a more concerned cluster depending on their responses. We found that especially participants at (a) younger age and (b) greater risk of a severe course of disease reported reduced mental well-being and seemed to be weakened in their psychological protective factors in our sample. These insights allow to provide tailored recommendations for preventive and immediate actions to promote psychological well-being and reduce stress.