It’s really simple: stand tall, feet shoulder width apart, then get in an athletic stance.
Athletic Stance - stand tall, feet shoulder width apart and then stick your hips out…your butt out. You will see how your knees flex without you having to bend them. Your upper body will have a slight lean forward and you should be in good balance. Now from this athletic stance go through your pitching motion keeping that athletic feel to it.
To get to know how it feels to load your hips, get a medicine ball (4-8 lbs) and hold it in front of you. Get in that athletic stance and keep your upper body in good posture weight even on both feet. Holding the medicine ball with both hands, bring it to your throwing hand side hip, keeping your upper body posture as still as possible while you bring the med ball to your hip. As you bring the ball toward your hip you should feel a load in your back hip/leg/foot. Now this is like a wood-chopper workout, you want to explode the ball up and over your Glove side shoulder. Initiate the movement with the hips, use that load on your back leg to fire the hips and do the work of lifting up the medicine ball for you. when you lead with the hips first you will notice how easy it is on your arms. You shouldn’t even have to put that much effort with your arms when you explode with your hips first, your hips did the work for you, your arms kinda just go for the ride. Hips explode, rotate torso then shoulders and arms go for the ride.
Hope this helps. Please comment/add/ask to this…