I don’t think anyone who’s really thought about it thinks true strength has anything to do with being physically strong . This is from Wikipedia:
On 5 or 6 August 1942, German soldiers came to collect 192 orphans (there is some debate about the actual number: it may have been 196) and about one dozen staff members to transport them to the Treblinka extermination camp. Korczak had been offered sanctuary on the “Aryan side” by the Polish underground organization Żegota, but turned it down repeatedly, saying that he could not abandon his children. On 5 August, he again refused offers of sanctuary, insisting that he would go with the children.
The children were dressed in their best clothes, and each carried a blue knapsack and a favorite book or toy. Joshua Perle, an eyewitness, described the procession of Korczak and the children through the Ghetto to the Umschlagplatz (deportation point to the death camps):
Mr. Korczak didn’t exhibit any physical strength, yet he was undeniably strong. Maybe strength is how you treat others? Or, like Mr. Korczak standing up for your convictions. I also think being strong has to do with being kind and honest. Sincere, dependable and doing what’s right. Not for any reward, either on earth, or in Heaven, but because it is just.
I think true strength is innocent. But, it’s also harsh and doesn’t mince words. It’s fighting when you know you’ll loose. It’s sticking to your opinion when everyone else is against you. And admitting when you’re wrong.
I will end with this:
Anyone can give up; it is the easiest thing in the world to do. But to hold it together when everyone would expect you to fall apart, now that is true strength.”