If you can work from home (big if) then you might consider looking into a standing desk + treadmill.
There are some decent options available. The "Autonomous" desk is great, I purchased JUST the legs and use an IKEA top to save money.
Now, I'm looking at the "Treadly" treadmill. Technically, this isn't an "under desk" treadmill, but it's the thinnest treadmill on the market and can be operated without the bars upright. So it's perfect for going under your desk, and then under a bed or a couch when you're not using it.
It has allowed me to work on some very cool robotics, and IoT projects. I've been able to learn a ton in the process about how computers work. Things like having to learn about how our FreeRTOS scheduler works, have been a fun process and provide some insight (albeit not 1:1) on how larger scale OS's work.
I feel like it's also made me a better programmer on the higher level stuff too. Hard to explain why though. It's not the kind of thing that makes obvious sense. It's not like knowing how to efficiently pack bytes into a struct, somehow helps you be a better Scala or iOS developer. That's just not the case. Rather, there's something about knowing the low-level stuff that just eases my mind when it comes to writing higher level code. I've always been the type of person that gets distracted by needing to know the deeper layer of how something works.
Even in undergraduate classes like biology, I needed to know HOW that mitochondria ACTUALLY handles metabolism. That's what I mean when I say that the lower level stuff "eases my mind". I can call a higher level function, or use some higher level framework, with a clear understanding of how it could (and probably) is implemented. That makes me a better developer, because I can stop asking questions and start making things.
Hey man, I started my career 7 years ago by teaching myself PHP, jQuery, and CSS. First real job was as a "full stack web developer".
I always was in awe of the low level stuff though, so I took every opportunity to move closer and closer to the hardware over the years. I'm now a firmware developer!
Point being, where there's a will there's a way. If you can align some DIVs, you can malloc() some memory and pack bytes efficiently in a struct :) It all comes down to where your interest is.
Uhg, I'd love to be that 50 year old when I arrive at the age. Sadly, I feel like I'm sliding backwards. Oddly, I feel like I was a better, more thoughtful, certainly more energetic developer in my 20's.
I think some of it may be that each job I've taken has forced me to change language / platform multiple times. I'm an iOS, android, C++, C, Java, and python developer. All on production level code. Never an expert of any.