Mine was also unplanned @45yo. The son took over the co and it went to crap. They took advantage of everyone they could and blessed the good Lord gave me the option not to take it. I could have easily went elsewhere but it would have been back to physical work and my body was done! Another very important thing is for older workers to keep up technically. I watched many that didn't keep up and their worth was basically nothing to the co but yet the workers felt the co owed them something for their yrs of service? Honestly I struggled at the end to keep up technically but knew how important it was. I think it was more that I was just plain DONE with the work and most definitely all the drama!
Keeping up with technology is never ending task for all workers in the modern economy. Especially if you're in the tech field as I am, you need to find study time to keep up with new stuff. I have done this successfully for almost 30 years but am now getting burned out by this. Thankfully though I'm ready to call it quits as I've always worked under the assumption that I could be replaced at a moments notice.