Do you have any references to the fMRI studies? I've never gone to the source for that sort of thing, and would appreciate a lead in getting started (not really sure where to even start looking).

The idea that we can biochemically run out of what powers willpower is a neat one. I feel like that implies there's something we can do to just replenish it, but making assumptions like that about complex things like brain chemistry is a great way to look smart while being not-smart.