ultimate productivity hack is saying no.

Do whatever favors you can, and be warm-hearted and direct when you have to say no.

When you say no, you are only saying no to one option. When you say yes, you are saying no to every other option.

the economist Tim Harford put it, “Every time we say yes to a request, we are also saying no to anything else we might accomplish with the time.”

No is a decision. Yes is a responsibility.

Saying no is an important skill to develop at any stage of your career because it retains the most important asset in life: your time. As the investor Pedro Sorrentino put it, “If you don’t guard your time, people will steal it from you.”

Steve Jobs, who said, “People think focus means saying yes to the thing you’ve got to focus on. But that’s not what it means at all. It means saying no to the hundred other good ideas that there are. You have to pick carefully.”

You may have to try many things to discover what works and what you enjoy. This period of exploration can be particularly important at the beginning of a project, job, or career.

Upgrading your no doesn't mean you'll never say yes. It just means you default to saying no and only say yes when it really makes sense.

If an opportunity is exciting enough to drop whatever you're doing right now, then it's a yes. If it's not, then perhaps you should think twice.

This is similar to the well-known “Hell Yeah or No” method from Derek Sivers.

What is true about health is also true about productivity: an ounce of prevention is worth a pound of cure.

More effort is wasted doing things that don't matter than is wasted doing things inefficiently. And if that is the case, elimination is a more useful skill than optimization.

Peter Drucker quote, “There is nothing so useless as doing efficiently that which should not be done at all.”