I swear by the go for a walk one.
Doesn't mean you'll magically be able to concentrate but context switches sometimes help focus on different issues. Plus it's healthy. Spend 3 days cooped up in your home trying to work from home and that walk outdoors is going to do wonders for your well-being.
It's like a quick reboot for your brain. Not a silver bullet, but sometimes it helps. A lot of the time it doesn't.