流水不腐，户枢不蠹（流水不腐，户樞不蠹）　

◎ 流水不腐，户枢不蠹 liúshuǐ bù fǔ,hù shū bù dù

[Running water is never stale and a door-hinges never get worm-eaten—practice keep one always fit] 常流的水不发臭,常转的门轴不遭虫蛀。比喻经常运动,生命力才能持久,才有旺盛的活力