It seems like my butt doesn't want to move, but it looks like it's slightly moving ㅠㅠ Oh, my body is too much.

Fixing below the waist + the thought that the crown of the head touches the floor.

This is right.

While going up, give a continuous feeling of contraction in the abdominal muscles when holding, and when going down.

Full stop fixed below the waist. Do not move the hips. This much is enough.