Wearing one changes your body's natural weight distribution. This affects your balance and changes how you ride, ultimately getting in the way of your progression. It's best to leave it somewhere safe.
You can easily monitor your center-of-mass along the length of the board just by being conscious of how/if each knee is bent. As indicated by a bent back leg with a straight front leg, your weight is currently shifted towards the tail of the board. This is putting a lot of pressure on the back edges (and very little pressure on the front edges) of your board, causing you to unintentionally force your back edges to bite & grip into the snow. This is compensated by "washing".
This is when you are primarily using your back foot to sweep the tail of your board from side to side, so the motion of your board can be imagined as a windscreen wiper. This is very tiring and is not good for control, especially at high speeds. Let's start to use the front edges of the board to naturally turn the board.
By bending your front knee, shifting your hips to near the center of the board, and keeping your shoulders relatively flat, you will shift your weight forwards which allows you to put more pressure on to your effective edges at the front of the board. These parts of the edge are "effective" because they are the ones to first start cutting into the snow and decide where you are headed. This is the foundation for effortless and stable linked turns where the board feels like it's turning itself.
By having more weight on the front foot you will now have enough pressure on these effective edges for them to help you initiate turns. To initiate toe-side turns, just drive your front knee horizontally away from your body. To initiate heel-side turns, you can horizontally open your front knee in a clockwise twisting motion. This is going to give you much more responsiveness and control. A different way to think about the motion is to imagine you are opening/closing a door with just your knee.
Without strapping in, try to emulate the weight distribution and front knee motions in the video's demonstration. This will help you get comfortable with these feelings when there are fewer moving parts.
Try it on a mellow run, after you've understood the feeling of this more balanced, slightly forward-biased weight distribution, as well as the knee motions for initiating turns. Be sure to constantly monitor your weight distribution by being aware of the amount of bend in each knee, as well as the levelness of your shoulders and the pressure you feel inside each boot.
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