How feeling more secure feels different than I expected

Thank you. <3

But the right amount of focus probably isn't "zero, ever", 

I agree! And I'm not saying that anyone should spend zero amount of focus on the question. Sometimes it is a relevant question to be thinking about.

But just as the right amount of focus probably isn't zero ever, the right amount of focus is probably also not "keep obsessing over it all the time". As you said, it's possible to focus too much on it. What I'm describing is a shift where it becomes possible to drop the question in the kinds of situations where it isn't useful, as opposed to being compelled to constantly run a (rather stressful) analysis about it, regardless of whether that's going to produce any useful information or not.

I agree (and I expect the person who originally asked this question to agree) that you can know what other people think about you on some level. With the experience that I call "being secure", you are content with having a sense of what other people think of you on that kind of a rough level, and also okay with the fact that in most cases you should have reasonably wide error bars on that estimate. With the experience that I call "being insecure", having reasonably wide error bars does not feel okay, and you are trying to get a much more narrow estimate than is usually realistic to extract from the available data, with the general consequence that you become oversensitive to noise.

I got the most value out of their previous courses / resources on something called "Ideal Parent Figure Protocol", though they're no longer offering that, since there was apparently some kind of a copyright dispute with the person who created that protocol. Archive.org still has their old "resources" page with some guided IPF meditations; I got quite a lot of value from just repeatedly listening to some on a daily basis.

They have a revised Attachment Repair course that uses a somewhat different sort of guided meditation instead, while trying to stick to similar principles; I've heard that some people consider the new meditation even better than the old one, but I haven't tried it personally.

Doing (some facilitated, some on my own) Internal Family Systems and Bio-Emotive Framework sessions were also useful for me for working through specific hang-ups and issues.

Here's what I wrote about IPF back in January; I've been intending to do a longer writeup of it, but haven't gotten around that:

Attachment theory says that young children develop a subconscious emotional model of how they should react to their caregivers in order for the caregivers to treat them well. In the best case the children learn a model saying that it's safe to just feel whatever they feel and that they are basically safe, but if their caregivers are un- or overresponsive then the children may develop emotional models that imply behaviors such as "best not to ask too much" or "need to be careful not to upset my caregiver by having the wrong emotions or needs".

Those models then form the basic template of how to relate to people other than your caregiver - feeling basically safe and confident and relating to other people in a healthy way that's neither clingy nor too obsessively independent, or not. And that basic foundation has a big impact on how things such as one's self-esteem, concern about what others think of you, ability to set boundaries, and romantic relationships develop later on.

Now attachment repair is aimed at reprogramming insecure learning that one may have picked up at a young age, by leaning into the fact that the emotional brain that the programming is located in can't reliably distinguish imagined experiences from real ones. So if you imagine yourself as a young child having the kinds of parents that are ideal from the perspective of developing a secure attachment bond, then this reprograms that original learning and can become as good as having had such a safe foundation all along, also helping you fix the kinds of issues that have developed later on due to not having a sufficiently secure attachment foundation.

Standard talk therapy typically cannot fully access this emotional learning, because much of it is laid down at the age of 6-24 months, so exists in a pre-verbal form. The attachment repair people claim that this technique can reprogram it, and that seems plausible at least based on my experience so far. [EDIT: I'm not totally bought into the precise claims about what age range IPF covers. It seems plausible to me that while it's more capable of tapping into very early life experiences better than other therapies, it does also affect insecure conditioning developed somewhat later in childhood; I've had stuff come up while doing it going up to at least age 7 or so.]

I took Cedric's earlier retreat on this and have been doing daily Ideal Parent Figure (IPF) practice afterwards. I've felt definite changes towards the better, with improved self-esteem, more of a sense of lightness in relating to other people, a sense of some early sexual hang-ups sorting themselves out, more thoroughly reprocessing and healing traumatic experiences which I thought I had processed already but which had still left lingering traces, and a general feeling of increased background safety that makes issues in general easier to handle. (Also a lot of other things but properly documenting all of it would require A Proper Big Writeup and I want to make sure that the changes stick before doing one.) Part of all of that is no doubt also due to unrelated inner work that I had been doing just before the retreat, but it's also obvious that doing the IPF continues to produce additional healing.

If you have done something like Internal Family Systems before, then it feels like IPF acts as a super-charger to it. When I'm doing IFS alone, it can often be hard to unblend from parts with an agenda in order to have genuine sympathy towards specific parts. In IPF, you don't really need to unblend, as it's not your job to solve the problem, but rather it's the task of the ideal parents. Your job is just to be a child and feel whatever it is that you feel and let them take care of any problems.

In theory I guess you shouldn't need this course / practice if you are already securely attached. In practice I expect everyone to have some insecure attachment conditioning, though of course if you don't have very much of it, then fixing it will be less useful than if you have a lot of it.

Transform Your Self by Steve Andreas is good for working on self-concepts. Kaj worked with it a while with personal improvements that were visible to coworkers and then we (some rationalists in Berlin) had a reading group for it. 

To give you one example of what it did for me personally, in 1-2 hours I adopted the self belief of "I'm attractive" that I previously didn't hold. 

Besides some very important internal work [LW(p) · GW(p)], there were a few external events that made me feel generally more secure.

Probably the most important one was that I've tended to often have the experience of growing close to a friend and spending a lot of time with them, only for their life to then head to a different direction where they couldn't spend as much time with me anymore. E.g. one of my close friends had a child and had to focus on family obligations, while another moved to the US to study. Combined with a series of unsuccessful romantic relationships, I had a sense of "I can't trust anyone I care about to stay in my life".

Now a few years back I moved to a small group house and grew close to someone who also lived there, until eventually she moved out to live together with her boyfriend. Now you might think that this would have reinforced my "everyone I care about keeps leaving me" schema, but it turned out to have the opposite effect, because she has very clearly and obviously wanted to stay in touch and continue to hang out even now that we're no longer living together. That gave me evidence that someone's priorities making them more distant from me doesn't necessarily mean that they'll practically disappear from my life, after all.