Windsurfing is a sport
Interesting, civilised thread guys.
Back to the original question: I have observed that kiters do not break a sweat. I don't say that meanly, just an observation. Unless taken to the extreme, it's an activity.
I'm into sports and health. Windsurfer is a real sport. I often sail no harness, a good outing works me up to 150+ heart rate in very few minutes. That's why I do it.
When the wind is light (<14 knots say), I dig up old board+ big sail and freestyle around, which is just as hard on endurance.
When I'd too old and broken for my current sport, and the day is coming soon it seems, then I'll consider kiting, alongside lawnbowling, big boat sailing, and chess. No offense anyone.