Sheryl Sandberg said this quote

“ Just being nice is not a winning strategy. Nice sends a message that the woman is willing to sacrifice pay to be liked by others. This is why a woman needs to combine niceness with insistence, a style that Mary sue Coleman, president of the University of Michigan, calls relentlessly pleasant. This method requires smiling frequently, expressing appreciation and concern, invoking common interests, emphasizing larger goals, and approaching the negotiation as solving a problem as opposed to taking a critical stance. Most negotiations involve drawn-out, successive moves, so women need to stay focused... and smile.No wonder women don't negotiate as much as men. It's like trying to cross a minefield backward in high heels. So what should we do? Should we play by the rules that others created? Should we figure out a way to put on a friendly expression while not being too nice, displaying the right levels of loyalty and using we language? I understand the paradox of advising women to change the world by adhering to biased rules and expectations. I know it is not a perfect answer but a means to a desirable end. It is also true, as any good negotiator knows, that having a better understanding of the other side leads to a superior outcome. So at the very least, women can enter these negotiations with the knowledge that showing concern for the common good, even as they negotiate for themselves, will strengthen their position. ”