I don't know where I read or heard that either, but over two years ago when I was going through some really awful times at work, it came to me like a thunderbolt as I was praying...
Be thankful for these trials, learn from them. In tears I asked Heavenly Father; Learn from them, What? That it hurts? Help me to learn.
Well, He did. Once I had humbled myself to thank Him for them. Boy oh boy was that hard to do.
I am still going through trials and tribulations, not the same ones. Guess that means that I
still have much to learn.