Concerned health officials in the Mexican capital hope to get residents in shape by offering free journeys in return for them burning a few extra calories. From Monday, dozens of stations in the city’s metro system have been equipped with special machines that, in exchange for 10 squats, will tell passengers how many calories they burned and give them a token for a free ride. The so-called “health stations” are a novel way for health chiefs to draw attention to Mexico’s dismal obesity levels.