Keeping a journal is particularly useful to resume your work.

Before lunch, or a meeting, or end of day, or when someone interrupts me and needs something, or any form of break, I "serialize" what I am working on in the journal, and then I read it when I am coming back.

In this way I can keep my mind clear and focus in the next activity.

It is also useful for standup meetings, retrospective meetings, etc... when you often need to describe what you did yesterday or this week.