Personally, I find having a space dedicated to work helps tremendously with this. When I am in my "office" at home, I am working. When I leave the office, I am not working.

Having that separation helps me "leave work" when it is technically at the same location. It does also require a good bit of discipline because it is easy to slip back into work at any point in the day.

Many argue that you should "work when you feel like it" but I personally find that leads to burn out. If I can keep a regiment that I don't deviate much/at all from, I am mentally healthier.