Background: University students have low levels of physical activity and high levels of sedentary behaviors that were exacerbated by the COVID-19 pandemic. Even before the pandemic, there was poor uptake of university sports activities. Therefore, it is essential to develop and test innovative programs to increase students’ motivation to engage in physical activity in order to prevent any future deterioration in their general health. Objective: This exploratory study was conducted to test the effectiveness of a physical activity program that was co-constructed with students. Methods: First, a workshop drawing on social design methodologies and the fundamentals of physical activity programs was conducted to assess students’ needs and desires in terms of physical activity. Second, the effectiveness of a program co-constructed with students on the basis of this workshop was assessed on physical and mental health parameters. The results showed that the workshop outcomes allowed the physical activity program to be tailored to meet students’ expectations (e.g., session duration and type of activities). This innovative physical activity program was found to improve body image, autonomous motivation, and certain physical parameters. At the end of the 8-week program, the adherence rate was 89%, and 83% of the final respondents expressed a wish to re-enroll for the following semester. Conclusions: Involving students and considering their wishes, needs, and objectives could facilitate the development of attractive and innovative programs.