Background: Physical activity is recognized as beneficial for older individuals in preventing falls. Achieving high adherence to exercise programs among the elderly poses challenges for administrations and healthcare systems. This study explored the facilitators and barriers perceived by both the participants and nurse trainers involved in an exercise program aimed at preventing falls in primary healthcare. Methods: Sixteen semi-structured interviews with elderly people who had participated in the Otago Exercise Program and a focus group of nurse trainers of this program were conducted between October 2018 and September 2019 in primary health care centers in Lleida, Spain. Interviews were transcribed and analyzed using inductive thematic analysis with Atlas.ti 8 software. Results: Analysis revealed five overarching categories and 17 subcategories. Key facilitators included personal motivation, the perceived benefits of exercise, and the supportive role of nurse trainers. Primary barriers encompassed factors such as the excessive duration of the program, not considering personal preferences for individual or group participation, and differences in physical condition among group participants. Conclusions: To increase participation and adherence to exercise programs, it is necessary to consider the important role of the nursing professionals that recommend program enrolment and the participants' personal motivations. The program with group sessions is a model that is easy to integrate into Primary Healthcare centers, which must always take into account the preferences and physical conditions of the participants.