Same here, the other day, I decided to give it a test on my Series 4, and while a one minute trip to the coffee maker, and pouring a cup of coffee got me a minute's worth of exercise, an hour of shoveling snow gained absolutely nothing. My heart rate was in a solid zone 3 during most of the shoveling, as I wanted to see if the notification worked, so I hit it pretty hard. Nothing for the snow, a minute for the coffee; go figure.