There were times when I thoroughly enjoyed my work, in fact most of the time. There were also times when I could not wait to leave a job, not because of the work but because of the working environment. One of those was arguably the cushiest one I ever had (little effort, good remuneration, good provision) but the atmosphere from the very first moment was absolutely appalling - for example, I picked up a systemic error in my first week there and pointed it out. This led to me being targetted, to the best of my understanding because the error had gone unnoticed for many, many months and its discovery now was bad news for those who didn't think to look for it (very obvious to me). I left as soon as I could. On other jobs the environment was truly excellent. All of my jobs were effectively "for the duration" of specific tasks and it was never likely that I would stay on with the same employer.
I stopped working because, in the niche area I was working, it was going to be impossible to sell my services once I approached 65. I miss certain aspects of my working life but I had no trouble stopping. Everyone is replaceable/expendable.