With the massive growth in Internet technologies, people have become wary of excessive Internet usage, known as compulsive Internet usage or Internet addiction. This study looks into how exercise is related to compulsive Internet usage. Previous research showed varying results regarding the relationship between sports habit and Internet usage; this project clarifies the relationship by investigating mediating variables in terms of interest in different aspects of sports, such as physical education, mastering sport skills, sports participation, and watching sports. Two survey studies were conducted. The participants were 232 male and 107 female Taiwanese undergraduate students in the first survey, totaling 339 students. The second survey had 233 males, 98 female students, and 2 who did not disclose their gender, with a final total of 333. The results reveal that interest in physical education (IPE) mediates sports habit and compulsive Internet usage. As long as the student had a habit of doing sports that increased IPE, this would in turn decrease compulsive Internet use. The importance of igniting students' IPE is discussed.