Sports clubs (SCs) are ideal settings for promoting health. However, existing health promotion (HP) interventions in SCs primarily target a single health behavior and male athletes, and evaluations provide little insight into their implementation. To overcome these limitations, the PROSCeSS intervention was co-developed based on the theoretical model of the health-promoting sports club and on multi-level and multi-determinant health strategies. The objective of this pilot study was to evaluate the implementation of the PROSCeSS intervention and to identify the factors influencing its implementation. A qualitative study involving meeting recordings, email and telephone exchanges, and interviews with representatives from 14 CSs was conducted. Although the number of SCs that completed the intervention is small, they believe they have a role to play in the health of their members. Their ability to develop health promotion activities and implement the intervention’s steps is influenced by available resources, the support they receive from their sports federation, and the capacity of a project leader (contact person) to get involved. The sports clubs that implemented the intervention put in place several strategies that allow them to integrate health into the club’s organizational, social, economic, and environmental practices and to develop new health promotion activities, such as adapted sports sessions and awareness activities on warm-ups, nutrition, and first aid. This study demonstrates the importance of understanding the specific characteristics of the contexts in which health promotion interventions are implemented. Because it led to a revision of the intervention’s phases and the development of a new evaluation design, it highlights the essential role of pilot studies in the development and evaluation of interventions.