Before you all rush out to your local park to try this for yourselves, there’s a catch. Murphy did all this wearing his military body armour. So we’re all clear, that’s a mile run, 100 pull-ups, 200 push-ups and 300 squats and another mile while wearing a vest that weighs just under 10kg. I see you slinking back to your armchairs…

Zuckerberg completed his Murph earlier this week in 39 minutes and 58 seconds. (His older two daughters, aged seven and five, completed a quarter-Murph, unweighted, in 15 minutes.) Understandably, he posted a sweaty, muscular and rather impressive selfie explaining the meaning of the homage and how it felt. He was one of thousands around the world.

The Murph Challenge is a CrossFit hero Workout of the Day (WOD); a workout issued by the fitness network which members are challenged to complete in the fastest time possible.

There are a number of hero WODs – created as a tribute to fallen military service people, and there are more than 23,000 posts on the Instagram hashtag themurph, featuring pictures of happy and very buff competitors.

Key to the challenge is a weighted vest. Designed like a thick waistcoat, with small weights distributed evenly in pockets, these are available online and do indeed look like body armour.