I remember my formtutor at school quoting Nietzsche (I think) to me when my life was really really falling apart. "What doesn't kill you makes you stronger". I almost killed her, because at the time it was so insensitive.
However, many years later I can say it to myself, but with the hope that it doesn'yt make you bitter or brittle.
Brittle is sort of like when you get so tough everyone is scared of you, which also happened to me. I kept wondering why I couldn't make friends but it was because I was so "out there" in terms of being independent, strong, tough etc that I couldn't find time to listen to anyone else's problems. As far as I was concerned no-one had the same sh*t to deal with that I had so they were all being whinge monkeys.
Now I try to be a little more tolerant and not bother whingeing ever ever ever because my life is sooo sorted and stable now.