'Galen may himself be responsible for the later fame of this particular plague. He had every reason to exaggerate the sickness that helped to make his name and it wouldn’t be his only piece of showmanship. He began his career tending to the wounds of gladiators (excellent medical training in a society where human dissection was frowned on), spent most of it as official physician to the emperor, and courted notoriety with public vivisections. His voluminous writings make up an estimated 10 per cent of surviving literature in ancient Greek, much of it memoir, pop philosophy or self-help.'

https://www.lrb.co.uk/the-paper/v46/n16/josephine-quinn/age-of-hypochondriacs