The Spanish inventor Pep Torres invented a cycle vending machine. Where you have to cycle to get a treat, e.g. you have to burn some calories before you can eat your candy.
Even the Times call this the The Human-Powered Vending Machine and put it in its top 50 best Inventions of 2009.
Absolutely a great idea though the only problem I have with it is that if I wanted say M&Ms before getting on the bicycle. I’m pretty sure that after a “bike ride” on it, I’m not up for just M&M’s I want more – like cake or a fry-up :)