I think the basic mechanism is:
You have an identity that says you're good at something, responsible, motivated, etc. that identity is the one that talks in meetings, promises to do stuff, signs up for things, etc. This is the part that would push back on the idea of being burned out as well, because it identifies with not being that way. Part of your brain is dedicated to projecting this identity out into the world.
Meanwhile you have another part of your brain which is your actual executive function, which responds to your needs and makes you want to do things. It will try to do what the first identity says, to a point, but if it starts wear down, be bored, be frustrated, etc, it will start to fail.
What's supposed to happen is that your first identity, or rather your whole coherent self with all of its parts, recognizes that something is not working and does something: takes a break, quits, stops working so hard, changes something, adjusts the identity to be healthier, whatever.
What happens instead is that those small failures are ignored and start accumulate into a larger and larger debt, of being behind, not getting what you need, and draining yourself of executive function to keep up with it. Eventually this becomes untenable and your brain just starts to shut down.
The way out is somehow reconciling the two. I expect that it looks like: first, realizing that you're drained and properly recuperating, then second, realizing that you're not getting what you need to stay driven and doing something about it. Just recuperating on its own isn't enough.