Uh, whenever getting food is expected to yield less of some necessary nutrient than is consumed by getting the food is a time when doing very little is the best option -- at least if the nutrient situation will probably get better in a few months. Also, if you are male, whenever you are seen as effective sexual competition by a male or coalition of males who are in a position to kill you or permanently damage you with little risk of bodily or reputational harm to themselves is a time when doing nothing impressive is the best option -- and in the EEA simply doing well at hunting, farming or making tools was probably seen as impressive by the women. Heck, I've gotten significant signs of interest from women just for sitting in a cafe in San Francisco and looking like I was productively engaged in writing things down on pieces of paper when the woman had no way to know what I am writing. Many writers say that industriousness is attractive to women. And, heck, in junior high school, I remember being attacked and my study supplies kicked around on the street by another male for appearing industrious.
In summary, it seems to me that one of the most profound differences between the EEA and modern life (at least modern life in the relatively well-run jurisdictions) is that in modern life, there is no reason not to spend a significant part of every day in effortful activity either physical or mental -- and note that effortful mental activity consumes many times more calories than "subsistence" mental activity does (I think: I should actually research that; personal experience is my main reason for believing it) and that mental activity accounts for 25% of the calories consumed by a human being (and I'm fairly certain of that last point)
And if getting thrown out of the band were not a large source of loss of reproductive fitness in the EEA, then please explain the natural human fascination with the theme as evidenced by the mass appeal of shows like Survivor (plot: every week, contestants vote to see which contestant gets thrown off the island) or Big Brother (plot virtually identical). Emotional reactions and tastes as strong and salient as that which are widespread in the human population should be assumed to be the result of selection pressures unless and until there is a good reason to believe otherwise IMHO. Well, I think I need to say a little bit more on this point. Yes, I am aware that many people, and a large fraction of the more thoughtful people, have an aversion to shows like Survivor and Big Brother. At least in the case of Big Brother I think much of the aversion comes from the natural human tendency to hold privacy violations (even when the violated have voluntarily ceded their privacy) as moral transgressions. And I think some of it comes from the fact that thoughtful people have noticed that this fascination with who is in and who is out and who is in danger of getting thrown off the island tends to have negative effects in modern environments such as your typical white-collar workplace. But mostly I think I have over the years gotten pretty good at telling which reactions are learned and which are innate, and the revulsion of many people toward shows like Survivor strikes me as a learned antibody to an innate interest in the theme.
Possibly doing nothing is a good idea for hunter gatherers in case of starvation, but that seems worth checking in the anthropology research. If starvation were a frequent risk, lethargy would surely been prompted by insufficient food intake, which is rare for humans today. We wouldn't just be lazy for that reason all the time; during times of abundance you ought to gather and store as much food as possible.
Apparently hunter gatherer bands were egalitarian, so it's unlikely people would have been beaten up by (non-existent) leaders just for hunting and gat...
Note: this post is basically just summarizing some of PJ Eby's freely available writings on the topic of pain/gain motivation and presenting them in a form that's easier for the LW crowd to digest. I claim no credit for the ideas presented here, other than the credit for summarizing them.
EDIT: Note also Eby's comments and corrections to my summary at this comment.
Eby proposes that we have two different forms of motivation: positive ("gain") motivation, which drives us to do things, and negative ("pain") motivation, which drives us to avoid things. Negative motivation is a major source of akrasia and is mostly harmful for getting anything done. However, sufficiently large amounts of negative motivation can momentarily push us to do things, which frequently causes people to confuse the two.
To understand the function of negative motivation, first consider the example of having climbed to a tree to avoid a predator. There's not much you can do other than wait and hope the predator goes away, and if you move around, you risk falling out of the tree. So your brain gets flooded with signals that suppress activity and tell it to keep your body still. It is only if the predator ends up climbing up the tree that the danger becomes so acute that you're instead pushed to flee.
What does this have to do with modern-day akrasia? Back in the tribal environment, elicting the disfavor of the tribe could be a death sentence. Be cast out by the tribe, and you likely wouldn't live for long. One way to elict disfavor is to be unmasked as incompetent in some important matter, and a way to avoid such an unmasking is to simply avoid doing anything where to consequences of failure would be severe.
You might see why this would cause problems. Sometimes, when the pain level of not having done a task grows too high - like just before a deadline - it'll push you to do it. But this fools people into thinking that negative consequences alone will be a motivator, so they try to psyche themselves up by thinking about how bad it would be to fail. In truth, this is only making things worse, as an increased chance of failure will increase the negative motivation that's going on.
Negative motivation is also a reason why we might discover a productivity or self-help technique, find it useful, and then after a few successful tries stop using it - seemingly for no reason. Eby uses the terms "naturally motivated person" and "naturally struggling person" to refer to people that are more driven by positive motivation and more driven by negative motivation, respectively. For naturally struggling people, the main motivation for behavior is the need to get away from bad things. If you give them a productivity or self-help technique, they might apply it to get rid of their largest problems... and then, when the biggest source of pain is gone, they momentarily don't have anything major to flee from, so they lose their motivation to apply the technique. To keep using the technique, they'd need to have positive motivation that'd make them want to do things instead of just not wanting to do things.
In contrast to negative motivation, positive motivation is basically just doing things because you find them fun. Watching movies, playing video games, whatever. When you're in a state of positive motivation, you're trying to gain things, obtain new resources or experiences. You're entirely focused on the gain, instead of the pain. If you're playing a video game, you know that no matter how badly you lose in the game, the negative consequences are all contained in the game and don't reach to the real world. That helps your brain stay in gain mode. But if a survival override kicks in, the negative motivation will overwhelm the positive and take away much of the pleasure involved. This is a likely reason for why a hobby can stop being fun once you're doing it for a living - it stops being a simple "gain" activity with no negative consequences even if you fail, and instead becomes mixed with "pain" signals.
So how come some important situations don't push us into a state of negative motivation, even though failure might have disastrous consequences? "Naturally motivated" people rarely stop to think about the bad consequences of whatever they're doing, being too focused on what they have to gain. If they meet setbacks, they'll bounce back much faster than "naturally struggling" people. What causes the difference?
Part of the difference is probably inborn brain chemistry. Another major part, though, is your previous experiences. The emotional systems driving our behavior don't ultimately do very complex reasoning. Much of what they do is simply cache lookups. Does this experience resemble one that led to negative consequences in the past? Activate survival overrides! Since negative motivation will suppress positive motivation, it can be easier to end up in a negative state than a positive one. Furthermore, the experiences we have also shape our thought processes in general. If, early on in your life, you do things in "gain" mode that end up having traumatic consequences, you learn to avoid the "gain" mode in general. You become a "naturally struggling" person, one who will view everything through a pessimistic lens, and expect failure in every turn. You literally only perceive the bad sides in everything. A "naturally motivated" person, on the other hand, will primarily only perceive the good sides. (Needless to say, these are the endpoints in a spectrum, so it's not like you're either 100% struggling or 100% successful.)
Another of Eby's theses is that negative motivation is, for the most part, impossible to overcome via willpower. Consider the function of negative motivation as a global signal that prevents us from doing things that seem too dangerous. If we could just use willpower to override the signal at any time, that would result in a lot of people being eaten by predators and being cast out of the tribe. In order to work, a drive that blocks behavior needs to actually consistently block behavior. Therefore attempts to overcome procrastination or akrasia via willpower expenditure are fundamentally misguided. We should instead be trying to remove whatever negative motivation it is that holds us back, for otherwise we are not addressing the real root of the problem. On the other hand, if we succeed in removing the negative motivation and replacing it with positive motivation, we can make any experience as fun and enjoyable as playing a video game. (If you haven't already, do check out Eby's Instant Irresistible Motivation video for learning how to create positive motivation.)