There is one thing which we can all do, every day, to keep our brains sharp and our memories intact.

Neuroscientists know about it. The mice in their labs spend a lot of time doing this.

Have you guessed what these mice are doing?

I put my keys somewhere safe. I know I did.

I was having a new desk delivered and the front door was open for a few minutes. I moved my keys away from the door to keep them safe.

Safe from me, it seemed, as I was still looking for them half an hour later…