My son and I played golf recently, and we were paired with two gentlemen who were retired from the military. Being the only woman in the group, and clearly less talented at golf, one man seemed very poised to give me pointers, suggestions and advice. My son called it "man-splaining." It stressed me out for a couple holes, but fortunately the threat dissipated quickly and we had a pleasant round.
I remind myself often to just keep quiet. For the most part, the world does not need my opinion. I admit that I have mixed success with this self-reminder!
I had a discussion recently with a friend regarding whether or not to speak up when we disagree with someone. I believe it's a case-by-case decision. It may be worth it to keep quiet to maintain peace. It may be so offensive that a response cannot be helped. Here is an example. A few years ago, my father-in-law, a Notre Dame graduate, in the presence of his wife and me, said, "Notre Dame really went downhill when they let women in." The noise I made and the look of horror on my face surprised him, and he went on to defend his position, until his wife said her classic line, "We don't need to talk about that now, Dick."
If I know that I will feel frustrated with myself if I don't speak up, then I will choose my words carefully and express myself. In the end, maintaining one's serenity is truly the most important factor.