流水不腐，户枢不蠹
liú​shuǐ​bù​fǔ, hù​shū​bù​dù

constant activity

流水不腐，户枢不蠹 (流水不腐，戶樞不蠹) liú​shuǐ​bù​fǔ, hù​shū​bù​dù
constant activity
literally meaning that flowing water does not rot and a door hinge does not get worm-eaten; used to signify that constant movement or exercise prevents stagnation and decay

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