A bunch of helpful comments on this thread already, I'll collect my all my thoughts so far here, in no particular order:

I know people have done/thought about writing such a thing in the past, but I approached this sequence in a completely different way. It was my New Year's Resolution to write productively every day for a year, as this seemed like the single most easily achievable and powerful mind level up I could attain. I made a bunch of progress in January but felt my thoughts going all over the place. Hammertime was the product of me sitting down for half an hour and figuring out a simple outline for writing with some system and regularity. Because I was already writing every day, the actual writing part was completely cost-free to me, whereas it sounds like possibly the major roadblocks in previous attempts.

My reasons for writing this sequence were, in clear order of importance: (a) to practice writing, (b) to review CFAR techniques for my own benefit, (c) to entertain, and (d) to teach instrumental rationality. With regards to (c), I have a belief that once you have decided on a thought to write about, the primary focus of the writing process is to make it as entertaining to read as possible, and this should come before making it useful.

The main issue was something along the lines of 'who am I writing this for?' Anyone reading the sequence would most likely already be famailiar with the material (a la someone on LW) and thus not really need the tools and advice (on account of the information being fairly wide-spread and easily accessable in the rationalsphere). On the other hand anyone who could really use the information is probably not going to be the kind of person reading this material in the first place.

I strongly disagree with this statement. I've been reading LW for about five years and "knew" about most of these tools abstractly without ever getting anything practical out of it. You can check the comments to Hammers and Nails and extrapolate that even longtime LWers have each only practiced only 5% of all the techniques we have, and that 5% varies wildly from person to person. It's not clear if what I've written so far actually helps in this direction, but I think a properly written sequence will actually inject readers with the moral fire to do the thing that they've known about for years.

This is part of the reason (the other reason being laziness) that I've eschewed science and citations - I think most LWers can produce on demand the psychological science to back up most of my techniques and claims, and adding them is low value. Some of this work has been filled in in the comments.

On the uncanny valley, I think what you're referring to is something different and benign: unavoidable opportunity cost, not so much practicing rationality causally making you worse at life. To me the uncanny valley refers to about three phenomena (that have all happened to me):

1. People becoming hyperaware of status games and deciding to play them consciously in a calculated, off-putting way. Anecdotally this seems to be a relatively common failure mode for students who go through SPARC. This is also my read on a good deal of unproductive LW conversation. Hint: high status isn't always better!
2. People learning about biases and deciding to solve them by pasting a post-processing fix on top(e.g. double all time estimates to fix planning fallacy), or making all decisions by System 2 because they no longer trust System 1. This is sort of classic "Straw Vulcan." One of the big failures of the Sequences, imo, is not detailing the important and serious reasons that many biases can actually be quite locally useful, even if they cause problems in areas they're not designed for. We need more Chesterton's Fence.
3. Rationalists beginning to see non-rationalists as normies, NPCs, or otherwise sub-human. It's not uncommon to see conversations and word choice on LW like: using "aliveness" or "more human" as largely synonymous to being better at rationality, saying in perfect seriousness "it's impossible to talk to normies because they have no concept of objective truth," or putting oneself in the tiny set of unlikely heros who are "actually trying."

I had something similar happen to me (with a different but equally inflammatory topic).

I didn't say anything I don't believe, but I think I could have said it in a more diplimatic way.

Is that the case with you too?

I am an endless repository of writing advice, mostly superstition and a bit of which I've written down. The most useful thing I've read recently is this excerpt from Pirsig's Zen and the Art of Motorcycle Repair:

Phaedrus found that rhetoric at the University level was taught as a branch of reason alone. He was also having trouble with students who had nothing to say. Especially one girl, who was a serious, disciplined, and hardworking student. She wanted to write an essay about the United States. Phaedrus told her to narrow it to Bozeman but she couldn’t think of anything to say. Phaedrus told her to narrow it down to the main street of Bozeman. Still nothing. He then said “Narrow it down to the front of one building on the main street of Bozeman. The Opera House. Start with the upper left-hand brick.”The next day she returned with a 5,000 word essay on the front of the Opera House on the main street of Bozeman, Montana.

We get blocked from our own creativity because we just repeat what we have already heard. Until we really look at things and see them freshly for ourselves, we will have nothing new to say. “For every fact there is an infinity of hypotheses. The more you look the more you see.”

The difference between "trying" and "doing" is something I touched on in Day 2: Yoda Timers. I think there's a closely related difference between "trying to write" and "writing." Namely: "trying to write" feels like looking for things you already know, whereas "writing" feels like looking at with fresh eyes. This is something a high school art teacher taught me as well, about drawing realism. If you want to write more, pick something and examine it in as high resolution as possible. The amazing thing about reality is its endless, almost unnerving detail.

"Mental energy" is a gigantic rabbit hole; you've asked a much deeper question than you think. I would set the frame less as "how do I boost my mental energy" and more as "what kind of crazy crap is sapping my mental energy," which suggests quite different sorts of ideas to try. I'm also quite worried at the thought of having so little energy you can't even read.

For starters, take a good look at your health in a broad sense: how's your diet? Are you sleeping enough? Getting enough exercise? Drinking enough water? Getting even the basics right here can make an enormous difference to your quality of life.

Beyond those basics there's mental / emotional / social health: do you have a strong support network? Are there people you can rely on for emotional support? Do you touch and get touched by others regularly?

Unfortunately most of the really helpful interventions here are really hard to do if you're starting out in a bad place. The fastest way to get out is probably to have someone else do it: you can swap "debug days" with someone else where someone spends an entire day trying to figure out with you your biggest bottlenecks and then tries to help you resolve them, and then vice versa.

Edit: There are also "tricks" that people sometimes discuss, such as splashing water on your face and so forth. They probably wouldn't hurt, especially the ones that are more health-oriented like drinking water and going for walks, but both my experience and my models suggest that most of them will not help in the long run.