Pick a corner and hit it, every time. Set the ball, strike with a clean technique, and place it into the marked corner with accuracy over power.
Strike from the edge of the box into the marked corners, alternating top and bottom, near and far. Emphasise a clean set-up touch, a still head, and placement over power. Both feet. Reset and repeat.
Fork it into your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block.