What does not kill me, makes me stronger
I think it was last year when I heard this expression again, but in a song. This is a funny phrase if you think in many thinks you can say about this. For example, the other day my little dog was eating a toilet paper sheet, and my sister mention something like this expression: "if that does not kill him, it'll make him stronger"... and I said " I really doubt that eating that, will make him stronger".
My point is that there are several things you can mention for this phrase, but they are not always true.
For those that are interested in know who was the person who really said that is: Friedrich Nietzsche (1844–1869)