> These days I can work from home when I want, but I don't because it stresses me out not to have a clear separation between home and work.

It's really hard. Takes some practice and discipline. One good way is to literally switch everything off (computers phones) at the end of the day. Stops you from "just answering that email" etc.

Another good one is leaving the house (drop off kids, buy breakfast coffee, whatever) end then when you are back home you are "at work". Then repeat when leaving work.