Build the habit of moving immediately after passing. With only four players and a central obstacle, a player who stands still after releasing the ball is instantly unavailable and the sequence stalls.
Set four mannequins as a small central box with a marker above and below, and put four players around it. Combine in pairs with a one-two around the box, then transfer the ball to a different pair. The rule is that you move to a new position after every pass you make. Keep the passes short, three to five metres, and play them past the box rather than around the outside. Two touch, then one touch once it flows.
Pass and move is instructed constantly and practised rarely. In most passing shapes each player has a station, and standing on it is not merely permitted but required, so the entire session quietly teaches the opposite of the thing being shouted from the touchline.
Four players and a central obstacle removes the option. There are not enough bodies for anyone to be surplus, so a player who passes and admires it is immediately a problem: the pair that has the ball has one option instead of two, and the sequence stalls within a pass or so. The correction comes from the exercise rather than the coach, which is always the better way round.
The box in the middle is what makes the movement meaningful. Without it, a player could shuffle a metre and still be visible, so moving would be a formality. With four mannequins occupying the centre, passing lines exist only at the corners, and a player has to travel a genuine distance to create one. That distinguishes real repositioning from the token half step most players offer.
The size is deliberate and worth protecting. Seven metres by twelve feels cramped, and the temptation when it gets scrappy is to spread out. Doing so fixes the scrappiness by removing the difficulty: in a larger grid there is always a safe pass available and nobody has to move to create one. Keeping it tight is what keeps the movement compulsory.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.