The COVID-19 pandemic has led to massive changes in almost all aspects of human life, including emotional states such as anxiety and fear, perspectives about healthy lifestyles, and psychological outcomes. This study aimed to disentangle the mechanisms that underlie the relationships of anxiety towards COVID-19 and fear of negative appearance with well-being, we also investigated the effects of cultural variations on levels of anxiety, fear of negative appearance, healthy lifestyles, and well-being. A total of 881 Indonesians ( = 172) and Poles ( = 709) participated in this study. Participants completed self-report measures of psychological well-being, anxiety, fear of negative appearance, compulsive exercise, and eating disorders. Multigroup structural equation modelling (SEM) was used. The results showed no statistically meaningful relationship between anxiety towards COVID-19 and well-being. However, it was found that, in the Polish sample, compulsive exercise and eating disorders mediated the relationship between fear of negative appearance and well-being. Cultural differences were also found in the mean scores of all examined constructs, with eating disorders being an exception. Therefore, this study highlights cultural aspects that determine emotional states, healthy lifestyles, and well-being.