RT Journal Article SR Electronic T1 The ‘Goldilocks Principle’: designing physical activity at work to be ‘just right’ for promoting health JF British Journal of Sports Medicine JO Br J Sports Med FD BMJ Publishing Group Ltd and British Association of Sport and Exercise Medicine SP bjsports-2017-097765 DO 10.1136/bjsports-2017-097765 A1 Leon Straker A1 Svend Erik Mathiassen A1 Andreas Holtermann YR 2017 UL http://bjsm.bmj.com/content/early/2017/07/12/bjsports-2017-097765.abstract AB