For them its physical exercise without any actual effort. It validates their "but I work out and I'm still faaaattttt" whines. What they don't realise is:  Yoga is not an activity that burns a lot of calories, it conditions muscles and improves flexibility but it doesn't burn fat. To get a decent work out from it you need to put in a serious effort. You should be just as ruined afterwards as if you just did 5 sets of deadlifts or ran a few miles. You need to keep the muscles under tension without leverage in order to improve the muscle condition. Not thrust yourself into a warrior pose with your momentum and hold it for the fourteen seconds it takes to snap a photo. It should fucking burn.