If January is boring you already, why not sign up to the Army Benevolent Fund’s historical code-breaking challenge.

Operation Bletchley: Berlin sees participants crack ten codes over 40 miles – wherever they happen to be based – before the end of the month.

With three levels to choose from, you can join the fundraiser for £15 and even link it to your fitness tracker.

To sign up visit the ‘challenges’ section of events.armybenevolentfund.org