Participants engaged in an evidence-based 12-week walking program.

In addition to the 12-week group walking program, participants engaged in the 5R Shared Leadership Program, which implements a structure of shared leadership and strengthens the identity leadership skills of the appointed peer leaders.

The manualised 5RS program aims to develop the leadership qualities of peer leaders by teaching them how to create, embody, advance, and embed a collective sense of 'us' in their teams. More specifically, 5RS consists of two key components that involve (1) implementing a structure of shared leadership, and (2) strengthening the identity leadership skills of the appointed peer leaders (Fransen et al., 2020).

Fransen, K., Haslam, S. A., Steffens, N. K., Mallett, C. J., Peters, K., Mertens, N., & Boen, F. (2020). All for us and us for all: Introducing the 5R Shared Leadership Program. Psychology of Sport and Exercise, 51, 101762. https://doi.org/10.1016/j.psychsport.2020.101762 Haslam, S. A., Steffens, N. K., Peters, K., Boyce, R. A., Mallett, C. J., & Fransen, K. (2017). A social identity approach to leadership development: The 5R program. Journal of Personnel Psychology, 16(3), 113-124. https://doi.org/10.1027/1866-5888/a000176

4-item Identity Leadership Inventory-Short Form

To assess participants' identification with their walking group, the investigators use the 4-item group identification measure (e.g., "I am glad to be a member of this walking group."), as suggested by Doosje et al. (1995). The cognitive, evaluative, and affective aspects of identification are evaluated on a 7-point Likert scale ranging from 1 (strongly disagree) to 7 (strongly agree).

Doosje B, Ellemers N, Spears R. Perceived intragroup variability as a function of group status and identification. J Exp Soc Psychol. 1995;31(5):410-36.

Group Environment Questionnaire - A higher score corresponds with a higher group cohesion

Warwick-Edinburgh Mental Well-Being Scale. It comprises 14 positively phrased items (e.g., "I've been feeling good about myself") rated on a 5-point Likert scale ranging from 1 (none of the time) to 5 (all of the time). A higher score corresponds with a higher well-being