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Try the Make Your Move challenge that will not only improve your balance but will get your core muscles working too.
He learned to walk on his hands while he was in the army and could go from the corner of a football pitch to the goal posts - and now enjoys doing it underwater during his daily swim.
You don't have to be 100 to get involved in International Handstand Day though! Whether you are on a beach, in a park, on a dance floor or doing your house chores you can take part.
On Saturday, 25 June people around the UK and around the globe will be showing off their handstands for the world to see.
To join in, post a photo or video of your handstand using #HandstandDay and we will be posting the best content on our Twitter and Facebook pages.
Meet John, who was born on 25 April, 1916.