The core of the cervical disc is comparable to a skippy ball: when the pressure on the skippy ball increases, the skippy ball will become flatter and broader. When a heavier person is on the skippy ball (this means there’s higher pressure), the skippy ball is compressed more than when someone lighter is on it
(because the presser is lower). The water in the cervical disc is pressed out of the core by the pressure. When the pressure disappears, the water is being absorbed back into the core, and the cervical disc will retrieve its original shape. By doing this, the cervical disc’s core feeds itself. You can compare this to a sponge. To prevent that the cervical disc dries out, it’s very important that you keep exercising.