Picture this scene: you’ve just started on a big task, blocked time to get it done when somebody’s head pops inside your office and drops the bomb:
“Heyyy, sorry you’re busy but can you do _______ for me? It’s very important and please get it done by today. Ok?”
To maintain peace, you give in and say “Yes”. Big mistake. You should have answered “No”, but that’s easier said than done, is it?