Every evening, at about the time the light starts to go, the dog and I go out for a short walk. Nothing ambitious — down the lane, round past the old fence line and back, twenty minutes at most. It started as a necessity, because she needs it. It's carried on because, it turns out, I do too.
A hinge between the day and the evening
Without it the working day tends to leak into the evening. I'll finish one thing and start another and suddenly it's nine o'clock. The walk puts a clear line between the two. I go out with the day still in my head and come back with most of it left somewhere along the lane. By the time the door shuts behind me, the evening has started.
Go without the phone
This is the one rule. Leave it on the kitchen table. Dusk is a short, changeable bit of the day — the colour goes out of the trees, the birds change, a lamp comes on in a window across the field — and you miss all of it looking down. Twenty minutes of nothing but noticing is one of the simplest and most restful things I know.
Any weather, mostly
I go in drizzle, in wind, in the first cold of the year with my hands in my pockets. Bad weather walks are often the best ones, and coming back in to a warm kitchen is half the pleasure. I'll admit I skip it in a proper downpour, and so does she.
You don't need a lane or a dog. A walk round the block at dusk does the same thing: it marks the end of the day, it gets you outside for the part most people miss, and it sends you home ready for the evening. It's free, and it's waiting at the same time every night.