Antonyms for the phrase "give a piece one's mind" which means to express your opinion openly include holding back or keeping silent, avoiding confrontation or conflict, and suppressing one's feelings or thoughts. Instead of giving a piece of your mind, you could choose to listen actively, empathize, and seek to understand the other's perspective. One could also opt to communicate assertively and respectfully, avoiding accusations or blame. Alternatively, one could simply let go and prioritize peace and harmony over being right, accepting and respecting differences. In sum, giving a piece of our mind is not always the best course of action, and there are many alternatives to consider.