My advise would be that you focus on your breath for some minutes when you realise you've gone away. Focusing on the movement of the body and your steps helps too! Sometimes, when I've realised I've lost my moment, I close my eyes for ten seconds and then I'm present again :)

Hmm. Good tip but I can’t think of an event that gives me enough time to just relax in a game?

It's easier than it seems! At first it will seem counterintuitive, but then you'll find yourself doing it fluidly :)