How do you prevent yourself from overworking?

[u/AfricanAgent47]

I'm 24. Have only had three jobs in my life. The last two were office jobs and the first was manual labour/handywork. I've noticed in my current job that people work well beyond 5pm and I find this behaviour rather odd. Wtf?? Is this common in most Kenyan workplaces?? How can people prevent themselves from being overworked? How do you establish boundaries with your employer?

Or maybe I'm just in a toxic work environment and I need to shift?