Ancient Greek philosopher Aristotle viewed laughter as “a bodily exercise precious to health.” But ---__1___some claims to the contrary, laughing probably has little influence on physical fitness Laughter does __2___short-term changes in the function of the heart and its blood vessels, ___3_ heart rate and oxygen consumption But because hard laughter is difficult to __4__, a good laugh is unlikely to have __5___ benefits the way, say, walking or jogging does.

__6__, instead of straining muscles to build them, as exercise does, laughter apparently accomplishes the __7__, studies dating back to the 1930’s indicate that laughter__8___ muscles, decreasing muscle tone for up to 45 minutes after the laugh dies down.

Such bodily reaction might conceivably help _9__the effects of psychological stress. Anyway, the act of laughing probably does produce other types of ___10___ feedback, that improve an individual’s emotional state. __11____one classical theory of emotion, our feelings are partially rooted ____12___ physical reactions. It was argued at the end of the 19th century that humans do not cry ___13___they are sad but they become sad when the tears begin to flow.