I work in the manufacturing industry with about 10 years in the field now. Worked for a very well known automotive brand as a manufacturing engineer. First job. Ok pay but really bad work environment. Left that job last year for a much better offering from another company that approached me.
Last place of work was extremely toxic and pretty much ruled by one manager who clawed his way up the ladder through the years. Typical shitty middle manager attitude towards employees. Complains a lot and never praises or appreciate the work put in. Constantly played favorites and found ways to screw over anyone that went against his ideas. Very loud with his words but that didn't reflect in his actions. I worked there for a while as it was my first job and I felt obligated to hang around because this manager kept feeding us with how it's bad “out there” and how difficult it was to find jobs in manufacturing. I was denied promotions due to “company policy” of needing people to be in certain roles for a minimum time period. When I announced my departure I got thrown counter offers and promises of promotions which I immediately declined.
After leaving I helped a few of my former colleagues join my new employer which made the previous manager throw a huge tantrum. Called me and demanded that I not help them and told me very sternly not to give references to anyone else (which is hilarious considering its none of anyone's business who I give references about). He has implemented a rule for the current employees of not giving references which he is trying to get HR to enforce (I have no idea how that's going to work). The image that he's portrayed so far has crumbled because when the two colleagues left they were humiliated and not allowed to leave gracefully (one of them was kicked out before the notice period ended which royally pissed off a lot of people). I'm currently helping another soul escape that hell for good.
This was a very important learning for me. Beyond the work contract there are no other obligations to your place of work/employer. Draw that line early on and make it clear. I now think of myself as a service provider or a private contractor. I provide a service and I get paid. Learning to switch off work is just as important as learning to focus on it.