Have a separate space as much as possible. A separate office is ideal, but even if you don’t, just allocate a space you can leave at the end of the day. Mentally, it helps me to disconnect. Close the door, I’m done with work.
I have setup desk similar to my office desk. For e.g. I have small office plant, Visa soccer ball, Frozen 2 Elsa figure, etc at my home desk along with Monitor, keyboard and mouse. Also, I have setup desk close to window so that I get lots of natural light. These things give me office vibes and keep me positive to work from home.
Where you work matters. Even when you don’t head to a separate building for work, it should feel like a separate space.
A silly one but in the morning I’ve started to bring a “tray” like a fancy cafeteria tray into my office and on my desk. It has — coffee, a big jug of water that i have to drink before noon, and breakfast (usually fruit or oatmeal). It’s a nice ritual that sets the tone for the morning. Then once the tray is all empty (gross from old banana peel sitting there all morning) it makes me get up and go and figure out lunch, or just leave the tray in the office.