Do you really need someone to help you figure out where DG lies on the excercise spectrum?
Of course it beats a sedentary lifestyle, but there's no way it's a substitute for resitsance training (to build mass muscle mass and increase metabolosim), or and legitimate cardio vascular activity like swimming, biking, etc, that raises your heart rate continuosly for 30 min or so at a time and really gets you huffing and puffing.
Obviously, the more siginificant the elevation changes and the longer the course, the more bang you get for your excercise buck, but disc golf is as mild as excerices gets - no more than a walk or disgustingly short hike. Frequent pauses for throws don't really help maintain an elevated heart rate. I'm not saying you might not want to rest after a couple of rounds or even take a nap, but c'mon, it is was it is.
DG is to excerecise, as the Yugo is to cars: certainly beats no transport (physical activity)at all, but it's nothing to brag about, and really can't compete with other, more substantial, alternatives.