Do you feel life is miserable?

Sadness

I was reading article on Shivaratri  by Sri Sri and then this one line struck me. "Be grateful for the happiness which leads to growth, and also for sadness which gives depth to life."

Being grateful for happiness is alright, but being grateful for sadness? How can or rather why should we be grateful for sadness? Those of you who have just come out of sadness or are going through it, would be in better position to understand my question.

Tomorrow is Valentine's Day. I assume few of you might have gone through sadness due to heart-break, break-up, absence of a lover or other heart related issues. Do you think the sadness you went through has given depth to your life?

You are free to answer it even if you never had any heart related issues, though I doubt you never had any! :)