Ok we live in a nudge world, where government policy is designed more often to nudge us than to put us in jail for something. Here is a nudge: Put obstacles on footpaths and make them undulating. 1. we might get our heads out of our phones 2. on uneven ground, every footfall is slightly different, requiring different muscles, so the loads on our muscular and skeletal systems are dispersed around the anatomy, rather than focussed on the same spots, as in the case of a straight hard pavement, where every footfall and stride is identical, leading to wear and tear on certain joints.