The hard truth about the trades is you need to start young, while you're body is able to take the punishment, so you have time to learn the skills to take a less punishing senior/ownership role by the time your back/legs/arms start to give out. This isn't insurmountable, but it needs to be planned for.

Look for jobs where your background gives you more of a leg up, and are done indoors, with a stronger emphasis on health and safety.

Things like:

Industrial Electrical

Automation Technician

Machine Operator

Millwright

Avoid jobs done for small crews with a more cowboy attitude, like most residential trades.

Look, a job is a job and work is well, work. As noted in the other comments trades are hard work. Far harder than a desk job. I would suggest not romanticizing the trades as some replacement for a desk job. Go do some trade work in your free time (go build a fence in the middle of the summer as an example) and really find out how much hard work it is. If you still enjoy it after being in 95 degree heat for 8+ hours while hauling thousands of pounds of concrete, then a job change might be right for you. But first try it as a hobby.

I say this with lots of experience. I do a lot of trades work as a hobby, but the reality is in most cases it is labor of love. I'd be more efficient with my time and money by hiring it out.

My advice. Take a year off. Renovate a house and see if it is what you want.

If you are burnt out. This is a good way to recharge. But the work is hard and it doesn't get easier.

Did this a few years ago and I it helped me get back to software engineering.

During the pandemic I was going stir crazy. I decided to immerse myself in some hands-on activities in the garage. Initially, I focused on restoration of antique tools. Then I had a small bit of blacksmithing. Then I learned the basics of welding. These activities were all great fun, very interesting to me, and gave me something to really look forward to for the weekends.

Not quite 2 months ago I launched a residential handyman business (no website yet). My day job is in software engineering, but I also have the handyman work as a part-time thing. So far, it's working out pretty good. My weekend work is completely different from my M-F day job. One of the things I like about handyman work is that it's not all the same. It's a bit of carpentry, plumbing, and electrical combined in various ways. I'm not a licensed plumber or electrician (nor a contractor), so I steer clear of jobs that require them.

I wonder how HN would respond if I asked "heya HN, what programming jobs would fit someone who has 10 years of TIG welding"

This is effectively what the OP is asking.

The cut in pay is likely to drive you back to software pretty quickly, but: the debugging and problem-solving involved in electrical work on old houses bears a striking resemblance to working with legacy software systems.

(New installation work is maybe less interesting, but if you're the sort of developer who enjoys logic-ing their way through understanding why a complicated, undocumented system is behaving the way it's behaving, and why did the last guy decide to connect this to that, a hundred year old house that's been gradually updated from knob-and-tube might be just the thing.)

My first question is why?

But I won’t judge and I think I can help! I would recommend HVAC or electrical work for a programmer. I manage the software team of a relatively large trade company which specializes in these fields. Many of our electricians are hobbyist programmers. Having done field work with both electricians and HVAC technicians I can say that both fields will provide you with challenging problems, and a familiar diagnostic and repair process to fixing software. I think HVAC is much easier to jump in to compared to electrical work (and you will still work on low voltage electrical components) so I would recommend looking for work in that space.

HOWEVER this is extremely hard work. I would not willingly trade places with any of our electricians. While it can be very fulfilling and enjoyable for the right type of person, what you’re talking about is essentially taking less pay to do more and harder work. And in that sense I would urge you to reconsider. But if it’s something that truly truly interests you, HVAC should be really easy to get into as long as it’s an active industry in your area.

What about permaculture/gardening?

IMO working with nature is a lot like programming. The genetic material (seeds) are like packages, the soil cycle is like memory management, and the water and sun are like your system's resources.

You get the satisfaction of building something beautiful (and eating it).

You are constantly learning about genetics, variants, processes and the language of plants.

There are role models and teachers creating new processes and testing theories (just like programming).

You are involving your entire body, puts you outside, and is amazing on your mind.

If you're looking to make money doing it, you could pick a high-value product like mushrooms, sprouts, or hot sauce and bring it to the farmer's market.

The way I see it (admittedly, as a 24 year old working in tech for the past 7 years), manual labour is okay, but definitely not something I’d do as a means to get by. My dad worked in construction for most of his life (mainly motivated due to debts incurred while he was locked up and taken up by my “mother”) and it has had an immense toll on his body, mostly back injuries and other non-reversable issues it has caused. But there were still many occasions where I went along with him to Finland, Sweden, and Norway as a “helper”, which have all taught me the value of hard work and dedication, pushing through whatever hardships you might have, and have generally been great for father-son bonding. Now that he however has exited that fieid (to work as a trucker which he loves because it’s basically “getting paid to travel long distances” which he loves), although I value the work done by tradies and have an immense respect for them (or at least the ones working as hard as my dad did), I still don’t see myself ever wanting to do that as a “job”. Since my dad has those skills, he still puts then to good use for personal needs (remodelling the house, fixing the roof, building a gazebo in his yard, etc), I still love going there to help him with all that, but much more as a father-son activity than as work.

stop developing for web and you'll probably enjoy programming again lol

Electrician should be your first option. Pay is often better than other trades and it is more intellectually demanding and less physically demanding at the same time. There’s a shortage now too.

Most electricians easily work into their 60s so age should not be a factor. You will need to start off as an apprentice but given your demonstrated technical ability, I would hope you’ll be able to identify niche jobs within the profession that you will give you leg up for more rapid advancement.

I'm late-30s.

About to start working on a personal project involving cement: making planters for small fruit trees.

The reason: to learn more about cement, since my plan is to set up concrete piers for a future cabin. And, to eventually learn masonry for making a concrete + rock house.

I do have a bit of back pain already from a desk IT job. However I am relatively fit and I think with more calisthenics I'll improve my back & ab muscles to reduce my back pain.

I've been watching https://www.youtube.com/@HVACRVIDEOS quite a lot.

The troubleshooting and diagnosis, as well as a combination of tech skills and curiosity is intriguing.

However, like most trades it is gated on years being an apprentice and being an apprentice at an older age is not easy because of the tasks given to apprentices.

CNC seems like a potential intersection of programming and trades. 3d printing etc might let you carry over some skills.

There will be a lot of opportunity in semi-automating residential/commercial property maintenance. Think robot mowers, smart irrigation/fertilization, smart composting ect. Lot of adoption potential from high-income Eco-conscious people that have already bought EVs.

Being an electrician always seemed interesting to me. I imagine this job to be ever more in demand as we move more and more from legacy energy sources (coal, oil, gas) towards electricity. The job can be dangerous though so that's a thing to consider