Faculty of Health, Medicine, Dentistry and Human Sciences, University of Plymouth, Plymouth, UK. University of Exeter Medical School, University of Exeter, Exeter, UK. Medical Research Council/Chief Scientist Office Social and Public Health Sciences Unit, University of Glasgow, Glasgow, UK. Department of Clinical Sciences, College of Health and Life Sciences, Brunel University London, London, UK. Institute of Applied Health Research, University of Birmingham, Birmingham, UK. Physical Activity for Health Research Centre, University of Edinburgh, Edinburgh, UK. Department for Health, University of Bath, Bath, UK. School of Social and Community Medicine, University of Bristol, Bristol, UK. Centre for Applications of Health Psychology, University of Southampton, Southampton, UK. School of Sport, Exercise and Rehabilitation, University of Birmingham, Birmingham, UK. Bristol Medical School, University of Bristol, Bristol, UK. Department of Psychology, University of Bath, Bath, UK. School of Sport, Health and Wellbeing, Plymouth Marjon University, Plymouth, UK. Bone and Joint Research Group, Royal Cornwall Hospitals NHS Trust, Truro, UK. PPI representative, Plymouth, UK.