Now get ready for good long periods of wilting fatigue, muscular exhilaration, heart-throbbing suspense, agonized tension, aching jaws, stiff, seemingly immovable joints. Because, when you draw human figures in any action, physical or mental, you are bound to feel the action intensely.
You cannot draw without feeling. And the more strongly you feel, the better cartoonist you are sure to be provided you can effectively transfer your feeling to paper.
Draw a man running like mad, fist clenched, jaw set. What happens to you? Try it. Put yourself wholeheartedly and deeply into the action you are drawing, and I guarantee you will feel it. You will be exhausted when you finish drawing a man running hard - if you put yourself into it. But when you finally do produce a drawing that is really convincing, it compensates you for the pain you felt when you were drawing.
Never draw any action without taking the pose yourself. Even if you have a model to pose for you, you must get the feel of it first yourself. Whether you look at yourself in a mirror or not does not matter. You will unconsciously draw convincingly if you are thinking how it feels while you draw.
Use the stick-figure or any other rough-in method you like and draw as many action figures as you can. Learn to exaggerate the action much more than would normally be probable in any figure. This is another secret of good cartooning.