Things to say no to:

Really great, impactful projects that you do not have time to commit to. 

Time sucking, pointless meetings.

A boss with impossible expectations. 

Mediocrity.

Any actions that will compromise your integrity. 

Delaying decisions that need to be made. 

Avoiding confrontation. 

Hiring someone who isn't the right fit even though you really need to fill the position. 

Fear.

You already know all this, but I found the reminder very helpful.