Now pushing 70 and retired for 4+ years, I don't seem to have any difficulties learning new or difficult things. There's some irritation at not remembering some of the prerequisites to certain topics that you once knew well, e.g., all the old trig identities. But after 50 or so years, that those memories are somewhat degraded is hardly a surprise. As others have noted, they're still in there, you just have to coach them out and polish the pathways. I seem to have more pursuits now than I actually have time for. Right now, I'm working through a calculus/diffeq refresher to prepare to go down the physics/electronics rabbit hole. I've spent some time playing around with Arduino and while it's fun and you can build a lot of things, it's mostly about what. And what and how were the dominate memes from my working life. Now I want to know the why behind the how on many subjects. And the math that has decayed over the ensuing decades is thus essential. For me, retirement has been like a new beginning. Live like you'll live forever. You won't, of course, but it sure as hell beats the "Waiting around to die" mindset.

I would love to have time to study those topics. However when I have spare time and I could devote a whole day to study, I realize my attention span does not make it.

So to anyone reading this, my advice is not to wait for retirement. I am lucky enough that my kids now prepare and go to school alone. So every morning I have about 45min when I can say fuck to the outside world including work and pursue studies I am interested in. I can't study any difficult or new subject after work.

Progress is slow but real.

Thanks for the advice for note taking. This is something I really have to improve.

Sounds amazing! Have you heard of/checked out Gleam which compiles to Erlang/JS?

Asking because if I was in your shoes, I'd spend all my time to invest in that ecosystem. I got a taste of it in my 3 month semester break where I was able to work on a lot of Gleam and Rust side projects. (Nothing to actually publish, but purely for fun and my own enjoyment).

I’m sticking with Elixir for now. I fancy myself a Lisp/Smalltalk style hacker&painter and like dynamic typing and macros, my current project uses Elixir and I’ve invested too much time & book money in Elixir.

That makes sense! I think it's a good idea to choose something and stick to it :) (especially if it's for fun)

The older I get the more I learn this lesson hehe.

Thanks for sharing. I really look up to people like you as I'd like to semi-retire around 55 too (13 years from now on).

I have a question for you: How do you assess your learning ability at 55? Let me explain -- I'd like to pursue studies in some Physics topics when I semi-retire (I can't do that now due to lack of time), but I'm not sure whether my brain is up to the job then. I know you are not studying Physics, but category theory is definitely non-trivial. How do you assess your ability to grapple with difficult theories?

A side question: do you exercise routinely, and if so do you think it contributes significantly to your health?

Thanks for any insight.

My wife and I are 57 years old, so I think I can address this. We finally got the younger child through to grad school and paid off all our debt, and now we can devote our time to what we want to do. Mostly, anyway - I'd like to be doing coding for pay, but instead I do technical translation.

But in terms of study - academic work - we're free. She's got a PhD in theoretical physics and has finally had the time to start publishing, including picking up quantum chromodynamics.

I've picked up my original doctoral work, too, which was on hold for thirty years while I supported the family. I've had no problems whatsoever tackling difficult topics - in fact, I've had less difficulty. I'm calmer, partly because I have to be in order to keep my blood pressure under control. I think I can do less in any given day, but I'm not even sure about that, because when I look back at items checked off over a week or a month, it's about what I wanted to get done.

So putting off study until you're 55 is not a bad plan. Keep reading about things in the meantime, of course. Take good notes. Keep things where you can find them in ten or twenty years. Write down your daily thoughts. You'll thank yourself later, trust me on this.

Love this! I’ve been mostly doing my hobbies as work for 20 years, but I’ve been having a blast getting back to deep pure math and PL research in the last 6-12 months which absolutely topped everything. It’s fully targeted towards my business goals which is ideal for me as I need a concrete problem to solve when learning. I’m 40 and this has been intellectually more productive than anything else I’ve done (feels like x times more than what I remember). It’s exciting and inspiring to see others doing it later in life as I wish I could keep doing it too.

Thanks a lot. I really appreciate your sharings. I'm glad that both of you manage to work on things you are interested in.

Did your wife get the PHD recently or when she was young? Reading through the lines I feel it was when she was young but I could definitely be wrong.

I also feel I don't have much to write down every day. Most of the time is spent on work chores or family chores. There are a few happy moments but that's it. May I ask what type of information do you retain?

She got her PhD in 1999, shortly after the birth of the kid who just finished his first year of grad school.

Sure, you're working, I totally get that. But you're also sometimes reading about stuff relevant to your eventual academic interests, if only articles you see on HNN or whatever. Sometimes you'll have a thought in the car. Develop the habit of journaling them when they come, in some place you won't lose over the intervening years.

You will be astonished at what you both do and don't retain over those years. It's mostly still down in there somewhere, but if you've got a few clues to unravel the threads, it'll help more than you think now.

Thanks for the tip. I'm thinking maybe I should at least register for a few pre-requisite courses and see what happens. I did have a Math Master degree but I forgot pretty much everything except SV Calculus and basic Matrix computation. Or I could just use Coursera to advance my learning -- for hell, the topics I'm interested in, e.g. General Relativity, do not need experiments so I might not even need a degree.

Regarding the last paragraph -- yeah I recalled that my first programming adventure was Foxbasing in the mid 90s. I definitely forgot all of those!

Good luck to you too.

> Write down your daily thoughts.

Can you elaborate on this? What sorts of daily thoughts did you write down and how did it help you?

I keep a notebook of ideas I want to pursue later. A lot of times if you don't write them down they'll be forgotten over the years, unless they're of major importance.

Over enough years, they will be forgotten, just like the names of the people you went to school with, unless you've got a way to rehearse them.

So a million years ago (the mid-90's), I was working with Doug Hofstadter and I had some ideas I wanted to follow up. Over the intervening years of raising a family, none of which do I regret, I never had the opportunity to actually do that - but I've done a lot of pieces of it, sometimes forgetting exactly where it fit into that original big picture.

Unfortunately, a lot of those pieces were logged on paper, but I've got electronic notes from about 2011 on, and a good content index has come in really handy for pulling out earlier ideas on various topics.

I've been working on that for the past year, and also scanning in a lot of the paper notes and starting to transcribe some of them. Looking back, there are some ideas I have every five or ten years, every time thinking I'm quite innovative.

Now that I've had the time to collate all that (and to read an absolute metric ton of literature I missed, an ongoing process), I've started to make consistent progress towards my original goals.

But just as a for instance - I have my readings and research bibliography from 1995 in machine translation. Most of that is dead as Carthage from a technical standpoint, obviously, but the philosophy has been invaluable as a starting point for recalibrating where I'm going.

But I've also got a lot of notes on related projects and just noodling thoughts I've had over thirty years of driving kids around in cars. I think the most important aspect of this is just keeping your mind active and focused on the things you find interesting, even if you don't have anything like the time you'd need to pursue them properly. Because sooner or later, the stars will align and you will. And when you do, your notes will be absolutely vital.

But I'm kind of obsessive about notes, so your mileage may vary.

I’m envious, reading EGB in the ‘70s is what put me on the path of computer science. I may yet try copycat or other creative analogy project in Elixir. I have the time, I’m retired :)

For the most part I'm staying near my field of study, programming, programming languages, theory about programming etc. In that way, just about everything I see I can relate to something I've learned before, I'm in true "I've seen it all before" mode at my age. For example the pattern matching and recursion-based "looping" navigation is just like when I went through my Haskell/Ocaml/Common Lisp/Scheme phase in the mid 2000's, so it was easy to pick up. The only new part of it is the actor-based concurrency model.

My foray into Category Theory so far has been reading "The Joy of Abstraction", which is a layman's book to CT. So far what's she's written makes perfect sense and would be mostly obvious to anyone who hangs out on HN. Moving up and down various levels of abstraction, the idea of "functions", as I read this I'm basically thinking it's what I've been doing for the past 40 years, not a big deal. We'll see as I continue in it.

Circling back to the original question, it's hard to assess my learning ability since I'm not venturing out into totally new territory for me.

When you have a job it's hard to fit in as much exercise etc. as you want, it's easier when you're retired. But also when you're retired it's easy to fill the time with other things, errands, as you get older medical appointments, and motivation is a little harder since you don't have deadlines on your projects. Work comes in spurts interlaced with reading, which is important but doesn't move the projects forward.

I do exercise regularly, especially after the heart attack. "Make these changes or you'll die" makes a great motivator.

Thanks a lot. I do agree that staying in familiar ground requires less brain work.

I do agree with the "more time without a job" observation. That's part of the motivation to pick up serious stuffs when I go semi-retire.

I hope you get well (the heart attack thing), but I'm happy that you make those changes when still young (relatively).

Out of curiosity, what was the trigger for the heart attack? I see you enjoyed your work, so I wonder if the stresses were beyond that? Or was it a diet/lifestyle issue?

I’ll chime in on this - my wife and I were just talking about it yesterday.

I’m mid 50’s. I had perfect 20/20 eye sight until about age 50, and now I can’t read almost anything without reading glasses - it came on quickly, but doesn’t seem to be worsening. I’ve always been a perfect speller (for the vocabulary that I use), but I’m finding I misspell 1-3% of what I type now (not typos). I’m also starting to misread headlines which I never did before (inserting words, misreading a single critical word, etc). It does feel like a tiny bit of haze is setting in, and I feel like this is probably normal.

Tell us how you retired.