The main aims of this study were to determine which sociocultural predictors of obligatory exercise are universal for young men or women and which are specific to particular cultural conditions (Polish or Chinese culture) and to examine the mediating role of eating attitudes. A cross-sectional study was conducted among Poles (n = 259) and Chinese (n = 208) aged 18 to 30. Descriptive and comparative statistics, Spearman’s rho, and multiple regression analysis were used. The main analyses showed that Internalization—Athlete was a common positive direct predictor of obligatory exercise among young Polish and Chinese women; Information and Internalization—Athlete were only specific direct positive predictors of obligatory exercise in young Chinese men; some variables in eating attitudes mediated the development of obligatory exercise in young Polish and Chinese men and women and indicated that there were cross-cultural differences. In understanding obligatory exercise among young people, attention should be paid to their sociocultural attitudes toward the body and eating, and cultural and gender differences need to be considered.