It is the ultra-simple fitness routine favoured by royalty: the Canadian Air Force five basic exercises, or 5BX, a full-body workout that needs no special kit and gets the heart racing.
Could it also be just the ticket to get your body fighting fit in the battle against coronavirus?
It worked for Prince Charles, who is said to do the routine every day in order to keep him fit and healthy.
In March the 71-year-old quickly bounced back after testing positive for Covid-19 – despite his age putting him at high-risk from the disease.
Charles suffered only "mild symptoms" and spent his recovery residing in his Scottish estate, Birkhall, amidst the health pandemic.
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Speaking to Country Life Magazine Charles shared: "Having recently gone through the process of contracting this coronavirus - luckily with relatively mild symptoms - I now find myself on the other side of the illness, but still in no less a state of social distance and general isolation.
"At such an unprecedented and anxious time in all our lives, my wife and I are thinking particularly of all those who have lost their loved ones in such very difficult and abnormal circumstances, and of those having to endure sickness, isolation and loneliness."
So how did he make sure a speedy recovery at 71?
Research has shown that even moderate exercise can have a positive effect on the immune system. It is also thought to speed up the recovery process if you do get ill with something like Covid-19.
It turns out that these ultra-simple fitness exercises used by Charles and the Air Force may have been his secret.
Here's the workout he swears by: