I am rereading Essentialism right now and the thing that sticks out to me the most so far is the importance of deliberate choice.
If you are not deliberate about how you choose to spend your time, someone else will choose for you.
In other words, you have to have the strength to say no to opportunities and requests from others.
As my platform has grown as an author, I get an increasing number of requests for my time to write, speak, and share advice. When these new opportunities arise, it is really important to think deliberately about how they align with your vision, strengths, interests, and the need in the world.
If you are not careful, you will end up doing many trivial things that take time away from the vital few things that make the biggest impact.