actually the same applies for all the ''sayings''. Most of them created through life and have even different meanings from person to person ( just like art :P ) Whatever doesn't kill you makes you stronger i am quite sure it is about inner strength you develop with every experience you have in your life.
It's that easy to completely destroy ( and funny if i may add) a ''saying'' that if we take a random one hmm just like give good take good we can see in real life mostly all the time this never happens. i give someone a dollar next day they steal me. i go say to a girl she is pretty i get a slam into my face. i save a man from a thief and next time i die in alley by his gang :P
The latter option is highly undesirable. All the rest can be traced. Although it is unlikely that this will make us stronger, perhaps more nervous)
that's why in those ''sayings'' we should better look at the bright side and positive way of thinking otherwise if we use half a dose of reality we are screwed :P think of it as a way to trick the brain and give to ourself more confidence and strength but still we must have a balance cause we are not superman! Anyway i am almost a year here and i haven't checked any of your posts but now it's about time to change that with a follow! :p
Thank you so much! Yes, I also think this is my omission)