Idleness is the rust of the mind.
游手好闲使心智生锈。
If you don’t practice your English often enough, one day it will become rusty. Likewise, if you idle around doing nothing, your mind will become dull. There’s a proverb that goes, “Idleness is the rust of the mind.”
如果你不经常练习使用英语,有一天你的英语会生锈。同样地,如果你游手好闲无所事事,那么你的心智就会变得很迟钝。俗云:“游手好闲使心智生锈。”