Career change for health reasons

Has anyone had to do it?
This is me:
Mid 40's. I've been working in an engineering office for the last 22 years. Being tied to my desk/CAD station like a veal calf all that time has resulted in a bulging disk and pinched sciatic nerve. I also had major abdominal surgery earlier this year and have since lost weight but the back, leg problem persists. The PT Dr. tells me it's due to the leaning forward position that we all do when working on computers and that I need to get up and move around more and, at this time, can avoid surgery. I find walking and standing for a while really feels good but of course I need to sit to design and new designs don't happen when I'm walking laps around the machine shop (I also walk during my lunch break).
At this time, I'm not desperate but I'm thinking it might be a good idea to at least think about changing fields to a position where I'm not required to sit in one place all day long. Since I returned from the surgery I find it harder to sit still all day long in my cubicle than I ever did before. Talk about life changing.
Funny but at this point I'm not thinking about the potential job's role as much as I'm thinking about the environment it takes place in.
Has this happened to anyone here? What did you do? How did it work out? I'm looking forward to any insights, experiences, ideas and all the details that anyone can share.
Thank you.

change position not career?

You could think about changing careers, but wouldn't it also be useful to think about changing position?  There are a lot of people who have moved to a standing desk, or a desk that converts from seated to standing.  A notable number of bloggers i follow in software development and technology (also largely seated professions) have made the change.  Google "standing desk" for a lot of options and other information.  Assuming you're in the USA or country with reasonable accommodation laws, you ought to be able to work it out with your employer as a medical issue.

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Dennis Sherman
6-1-2-7

Agreed.  Look at a standing

Agreed.  Look at a standing desk, particularly one that can be adjusted from a standing to a sitting position back and forth.  A couple of staff in my area are using them and I'm considering it.  We have ones that work for multi-monitor set ups for developers, so CAD should work.  We also have a program people can load on their computer to remind them to take a 5 minute ergo break periodically (default is every 45 minutes).