The key to creating speed is staying relaxed and swinging without tension. Mike Malaska suggests that words like "trying to hit the ball harder" or "pound the ball" impact how you swing. People usually tighten up when they try to hit the ball harder. Thinking about it from the perspective of creating speed will help.
Mike tells a story of how sprinters in relays would start to grip the batons tighter as they tried to go faster. This actually made them slower because just gripping the baton harder created tension in the shoulders, neck, head, and body. They learned that when they accelerated and didn't tighten up their hands, that made them faster.
Gravity plays a role in creating speed. This principle applies to golf too. Hold your driver above your head with both hands and drop it. As you can see, it produces quite a bit of acceleration. If you want to create a lot of speed, make sure on your backswing that you get your right hip out of the way and shoulders turned.
Also, ensure that your arms go up because if they do, they must come down, creating a downward force. If you pin your arms against your side and have a shallower swing, you may have more control, but you won't have any speed. When you come down, your left leg plants and stops the forward motion, just like in a baseball swing. Your left leg pushes back your left hip and accelerates the club through the ball. When you hit a golf ball, it's not about driving your legs or spinning your hips.
Mike takes us through a few steps to create speed and more distance. First, get set up and get your right hip out of the way on the backswing. Make sure that you are using the lever system. Make some practice swings and get a feel for how that flow works. Now, as you come down, focus on your left leg pushing your left hip out of the way. Make some practice swings. To get your maximum distance, ensure you have enough arm swing and that your arms are soft.
Combine all the steps and accelerate the club forward. Remember, no tension, get out of the way, let your arms swing up so they can drop, and then time your left hip getting out of the way as your club comes through the ball. You will create the maximum amount of speed out of your arm swing, body motion, and the lever system.