流水不腐，戶樞不蠹
running water is never stale and a door-hinge is never worm-eaten;a thing in use never rots
流水不腐，戶樞不蠹liú shuǐ bù fǔ,hù shū bù dù
戶樞：指門的轉(zhuǎn)軸；蠹：蛀蟲，這里指蛀蝕。流動的水不會變質(zhì)腐臭，經(jīng)常轉(zhuǎn)動的門軸不會被蛀蝕。比喻經(jīng)常運(yùn)動的東西不易被侵蝕，也比喻人經(jīng)常運(yùn)動則不易生病。running water is never stale and a door-hinge never gets worm-eaten, practice keeps one fit