Background: Exercise plays a crucial role in addressing the increased cardiometabolic morbidity and premature mortality in people with schizophrenia spectrum disorders. When delivered in community-based settings, exercise may also reduce loneliness, while promoting overall physical activity behaviours. Skilled instructors are essential to deliver effective community-based exercise; however, knowledge about their roles and required training is lacking. We aim to explore various stakeholders’ perspectives regarding lay exercise instructors’ roles, and the required elements in an educational programme supporting the delivery of community-based exercise for young adults with SSD. Methods: We used semi-structured homogeneous focus groups with representatives from different stakeholder groups (i.e., including representatives of clinical staff within mental health, physiotherapists, exercise instructors, young adults with schizophrenia spectrum disorders, and relatives of individuals with schizophrenia spectrum disorders) targeted or affected by a community-based exercise intervention. Data were analysed using qualitative content analysis. Results: We conducted six focus groups comprising a total of 30 individuals representing five different stakeholder groups The analysis identified three categories: (i) awareness and understanding of mental illness, i.e., providing basic knowledge to dispel common myths and stigma regarding mental illness (ii) protecting youth identity, i.e., supporting the feeling of being more than just a patient, and (iii) promoting exercise as a shared activity, i.e., a communal pursuit, fostering personal growth among participants, their peers and the instructors. Conclusions: An educational programme for lay exercise instructors delivering community-based exercise targeting young adults with SSD should empower the instructors to assume the role of guardians of an inclusive exercise culture. Educational elements identified were adapted and integrated into an educational programme implemented and evaluated as a part of the Vega trial. Our results may be transferable to the education of lay workers in mental health care where the aim is to facilitate sustainable, recreational, community-based activities.