One interesting attempt at this was a health intervention in Cambodia. Rural villagers were having iron deficiencies. A cheap countermeasure was to put lumps of iron into boiling broths or water that people were going to drink, but it was hard to convince locals to actually follow through.

So, they made iron lumps in the shape of fish (a local good-luck symbol) and handed them out - increased compliance a lot.

http://www.bbc.com/news/health-32749629