The problem here is that "internal strength" is a longstanding translation ..... It's not like "internal strength" has only been used in the last couple of months and so its meaning is still up for grabs.
`When I use a word,' Humpty Dumpty said, in rather a scornful tone, `it means just what I choose it to mean -- neither more nor less.'
`The question is,' said Alice, `whether you can make words mean so many different things.'
`The question is,' said Humpty Dumpty, `which is to be master -- that's all.'
Through the Looking Glass, Lewis Carroll; Chapter VI, Humpty Dumpty