My wife and I have had our Sport models for a few days now and we are still trying to figure out what the watch considers exercise. It tracked my running no problem, but we went on a 4.5 mile walk and it didn't track anything. Runkeeper said I burned 400 calories on the walk and the activity app basically implied we sat on the couch. My wife also did a 30 minute cardio intense workout at home followed up by 30 minutes of yoga and altogether it tracked 15 minutes of exercise....any ideas?