First world kids who have the luxury of setting high expectations for themselves tend to beat themselves up most when they are in the midst of discovering whether or not they can actually meet those expectations.

I would like to say that this explanation you've put together manages to sum up the most recent period of my life perfectly. (I'm 27 and 9 months, even the age range fits well.)

Considering the cognitive load I was under earlier this morning trying to resolve problems related to exactly this, The feeling that I'm left with is the one Eliezer mentioned in http://lesswrong.com/lw/of/dissolving_the_question/ where all of the unexplained bits and pieces that I was going crazy over are just gone.

I even thought "But wait, what if there is something I missed that would make this a bad explanation that I'm letting myself get fast talked into." (mental review) "Can't find a thing, it really does fit every bit of evidence I can think of."

Thanks!

I completely misread self-flagellation as a hyperbole for self-criticism. Thanks for substituting it with self-abuse to help me out. I really do apologize if my tone or words came off as hostile or aggressive. I really like your idea

first world kids who have the luxury of setting high expectations for themselves tend to beat themselves up most when they are in the midst of discovering whether or not they can actually meet those expectations.

It is exciting finding something you have never thought of yourself. I think it is a good idea, but I still do not agree that 28-29 is the endpoint. I think you are correct in calling it a threshold, but not a final threshold.

I am a runner. When I first started running I could barely run 2 miles. It was hell. I kept trying to push myself to do it faster, which ultimately was self-abuse. My muscles were not ready, my heart was not ready, my bones were not ready, and mentally I was not ready. After about a month of running 2 miles on the weekdays and 3-4 miles on Saturday, I finally found myself able to run at a speed I liked without killing myself. I find this to be analogous to you at 28-29 being able to manage your time where you were able to be competent without self-abuse. My point though is after breaking that threshold my body was ready to undertake a new threshold. I then began running 5 miles every weekday and 7 on the weekend. The first time I did this it felt exactly the same as two miles, hell again. However, my adjustment to running 5 miles only took 2 weeks, instead of the month it had taken me to get used to 2 miles. When I transitioned to 7 miles daily it still took about two weeks to get used to it without any pain, but the pain was significantly less than my starting pains. I know this is an analogy, but I believe to some extent this applies to life navigation as well. It is probably a much slower process, but I think it is possible to reach new competency thresholds until somewhere between 40-60. I apologize for the large range; this is a hypothesis that I have yet to have the means or method to verify. The idea though is that there is some point in age where you cease to be able to learn radically new systems of thought, habit, or emotion.