(as) hard as nails humorous informal slang
Having great strength of body, mind, or will, and resilience in the face of hardship or pain
Don't think that she's old, she's still as hard as nails!
At home, she is a warm-hearted and sweet girl. But at work, she is as hard as nails!
Because her family is so poor that her parents cannot afford the high costs of education, she has to work and study at the same time. She is hard as nails!
This idiom can be considered to derive from the 1860s.
Used when something unpleasant has happened that has spoilt what you intended to do
Oh, no, that’s torn it! I’ve left my wallet at home!