Healthy living environments create healthy physical activity-related habits (ELEVATE): A protocol for a smartphone-based mixed-method study - Marco Helbich; S.M. Labib; Isabel Liedtke; Danielle Sent; Ronald Crombag; Dick Ettema; Hanneke Posthumus; Saskia van der Zee; Mart Reiling; Susan Ruinaard; Anneke van Mispelaar; Aarnout Brombacher; et al. (PLoS ONE, 2026)