Remember not only to say the right thing in the right place, but far more difficult still, to leave unsaid the wrong thing at the tempting moment.
In your professional life, there are so many complex environments; Customers, accounts, employees, vendors, colleagues, peers, bosses and more. When you work with people, you work with emotions and all can have a different perception of the reality of a given situation or conversation. Not only what you say, but how you say it can drastically change the impact. Sometimes the best action is inaction and resisting the temptation to say anything.
And yes…sometimes it is much easier said than done, but it is those situations that test your internal mastery most.