I don't know if this
(Fotoarchive Tom Wagner) qualifies as excercise, but it is a fun picture to look at
I think CP Mary was elected the most athletic princess by Hola! magazine a couple of years ago - there was a picture of her mountain biking. Most royal sports seem to be of the sailing/riding/golfing variety though - has anyone (par the Grand Duke) of them ever for example finished a marathon?
"Contrariwise", said Tweedledee, "if it was so, it might be; and if it were so, it would be, but as it isn't, it 'aint. That's logic."
From "Through the Looking Glass" by Lewis Carroll