From a famous passage of the 《
孟子》: when Heaven is about to give someone a great task (
天将降大任于斯人也), it first tries them with hardship,
所以动心忍性,
曾益其所不能 "so as to rouse their mind, toughen their nature and add to what they could not do". Here
忍 means "to harden", not "to bear".