I have been involved in many projects throughout my work experience. What I've noticed is that whenever I was really involved, I was thinking about my ongoing projects all the time. There was no schedule, night, weekend, holiday or whatever the occasion, when I wasn't connected to my work. It slowly became a part of my life and I got used to doing it. Is it because I love what I do? Is it because I am able to motivate myself?
It's not necessarily about people hating their jobs, but I've noticed they don't integrate them seamlessly to their lives. Once they will experience the real satisfaction of their work, once they'll get the feeling of success, I'm sure their work habits will change as well.
For me, when I'm involved in a project, it works very well to dedicate myself to what I'm doing, it doesn't matter if I'm watching a movie during the evening, I'm always trying to find opportunities, ways of improving, things I could apply to my work, that could help me succeed.
Working during the weekends, especially from home, has become something normal for my activity. Sometimes I don't even realise I'm working; I am sketching ideas, writing stuff, organising my documents and my tasks. I really enjoy doing that and it gives me confidence on Monday morning, when I am well prepared, organised and ready to action.
Obviously, it depends on the nature of the job, but whatever it is you are doing, by doing it right, improving your work process and being involved at all times, you will to start creating your personal values, your personal work process and your principles which will help you throughout your entire life.
So, if you don't choose to actually work on weekends, the least you can do is think about your activity, brainstorm your challenges and try to mentally solve them. That's how our brains work, the more we get used to a specific thing, the easier it is for us to deal with it later. Think about your problems, analyse them, structure your thoughts and you'll enable yourself to better deal with your challenges!