Good questions! I do think an energetic approach to life can be contagious. I have several friends who seemed to be coasting into couch-potato lifestyles that snapped out of it when the rest of the social group all took up bicycling. I have a friend who used to keep a family tree of folks he inspired into running regularly. I might be able to compile my own list who have started biking. Lots of neighbor friends have started cycling since I started evangelizing it years ago.