This is probably the most essential skill you want to learn when you feel burned out: it is simply the art of saying "no".
The reason you might not use that skill is because you perceive saying "no" as the fact that you are not good enough.
Basically, you want to feel responsive. You want to give others the impression that they can rely on you.
This is why you go ahead and respond to other's needs and demands.
When you say "No", you break the flow and design a new rule.
It takes courage and understanding to establish this new limit in an empowering way.