17. If you can’t say “no” easily, you can’t be trusted.
“No” is an acceptable answer even without a reason.
Kevin Kelly • Excellent Advice for Living: Wisdom I Wish I'd Known Earlier
When you say no, mean it, and you won’t needlessly lose your time.
Peter Bregman • 18 Minutes: Find Your Focus, Master Distraction, and Get the Right Things Done
We agree to many requests not because we want to do them, but because we don't want to be seen as rude, arrogant, or unhelpful. Often, you have to consider saying no to someone you will interact with again in the future—your co-worker, your spouse, your family and friends.