The heir to the throne, who's a well-known fan of complementary medicine, was reduced to stitches as he was introduced to the art of chi kung, a form of energy exercise.
As an instructor showed him to perform moves such as raising two imaginary energy balls above his head, the royal started laughing with his exercise partner, Eva Hamilton.
The Prince was visiting Eva's Warrior Programme, a three-day course for ex-Service personnel, in Fulham, west London.
Founded in 2007, the programme uses chi kung and other therapies to help ex-servicemen and women overcome emotional and mental problems after leaving the forces.
"For the ex-soldiers it works on the breath, teaching them how to breathe again, it helps them release tension and is good for arthritis," said Charles's instructor Guy Ho.
"The Prince was focused but he dropped the ball twice – I had to find his energy ball. He had wonderful energy, you could really feel it."