Does anyone happen to know of reliable ways for increasing one's supply of executive function, by the way? I seem to run out of it very quickly in general.

There are a handful of specific small fixes that seem to be helpful. For example, having a capture system (which many people are introduced to by Getting Things Done) helps decrease cognitive load, which helps with willpower and energy. Anti-akrasia methods tend to fall into clusters of increasing executive function or decreasing value uncertainty / confusion. A number of people have investigated various drugs (mostly stimulants) that boost some component.

I get the impression that, in general, there are not many low hanging fruit for people to pick, but it is worth putting effort into deliberate upgrades.