Biggest trick is taking breaks, it is so easy to push past when you'd really have liked to stop for lunch because you think you're almost there or skip your usual break for a coffee. Set timers if you need to. I tend to rely on my partners to remember to ask for breaks or suggest breaks when they seem distracted or like they are flagging.

We update assignees to reflect when more than one person is working on something but we never assign work to individuals or pairs. We use an aggressive WIP limit of engineers/2+1 to prevent a ton of in flight tickets but other than that we're quite free to move around as long as we're moving the stuff on the board right-wards.

I think that's a thing that contributes to our success at pairing actually. Since we all value schedule flexibility quite highly we get on well with pairing a bit when we happen to have synchronized working time and working on independent subtasks when that is more convenient for us.

https://tuple.app/ - this tooling helped a ton, it's expensive but worth it to reduce the friction to start a pairing call to 0. Pairing on zoom, slack, meets, etc. is all much more painful. VS Code LiveShare esque things are free and can probably work as well with some discipline.