Within the fields of e-health and persuasive technology, research indicates that intervention websites can motivate people to adopt healthy behaviours, such as quitting smoking, exercising more, and eating better. Frequently, these online interventions are individually tailored programmes, resembling two-way interpersonal therapy. It is now conceivable that health campaigners can deploy mass-interpersonal campaigns, where online media are used to engage large populations in automated personal relationships, similar to relationships people have with their doctors, councillors, trainers, and trusted friends.