[TeMPOraL]

I think GP isn't talking about energy used to perform an exercise, which (IMO) indeed comes from "a completely different place". I read their comment as talking about energy required to start doing an exercise, day in, day out. This, at least for me, comes from the same place as energy needed to start writing code at work, or to get out of the house and run and errand. Burnout happens when that energy source becomes depleted or unreliable.

Based on my experience (including lack of the ability to stick to any exercise regimen long-term), I second GP's post.

I also agree that doing exercises helps recover that second type of energy. It's a positive feedback loop - but the problem is, you won't be able to start it if you're too depleted on the "starting energy". Like with an ICE car - the engine does recharge your battery, but you won't be able to start it if the battery is already dead.