I'm by no means an expert but I would say do some looser sketches as well as more finishing drawings like this. Sketching skills and drawing skills are two very different skills. Get a sketchpad just for quick loose gestures/ sketches and don't try to make them prefect. Don't even show anybody these sketches that way you feel less obligated to make them perfect. (thus making them less stiff and more fluid) also there's an incredible book called: Figure drawing design and invention by Michael Hampton. that MFer can do gestures like a pro haha The book goes over balance, Timing, "the about to" pose, etc. It will really help you put more life and action into the figure. Making the figure look mid-action rather than in between actions. It also might help to think of the gesture as an exercise in the way lines move the eye thru the figure.

intersting stuff! Love loomis definitely gonna add this to my reading list