Me too, I usually chose my battles. If I express my opinion it has to be in a polite way, I am all for harmony !It completely depends on the situation. I usually speak my mind, but there are times when that is not such a good idea.
I don't believe in a one size fits all approach - sometimes you have to speak up no matter what and sometimes you have to stay quiet at all costs - the art is to know when which is appropriate.
I find that still difficult but I am learning - .