Lingling Gao

• A healthy lifestyle plays a key role in maintaining both the quality and the length of life. Interrelation of behaviors (internet use and health behaviors) and higher-level goals (perceived quality of life, work-life balance) are examined in this research. The first study focuses on the interrelation between internet use and physical activity. While doing so, it identifies the differences across age groups. The second study focuses on the different contributions of work-time and leisure-time internet use to perceived quality of life, taking stress management and health behaviors into account. The third study focuses on the interrelation between multiple health behaviors and work-life balance, as well as the mediator roles of perceived stress and problematic internet use, and the moderator role of the resident countries. The results of the first study show positive associations between physical activity variables. Positive associations between internet use and physical activity emerges in late adolescents, whereas negative associations between internet use and physical activity planning emerges in middle-aged adults. The results of the second study reveal that leisure-time internet use, but not work-time internet use, is positively associated with problematic internet use. Participants whose work-time internet use could be considered balanced indicates a higher perceived quality of life. The results of the third study indicate the mediator roles of perceived stress and problematic internet use between health behaviors and work-life balance. Among the residents of Germany, a partial mediation is revealed, whereas among the residents of China, a full mediation is found. Conclusions are given in the form of research, practical and theoretical implications. In today’s digital society, a proper combination of multiple health behaviors and appropriate internet use can benefit individuals’ quality of life and work-life balance.