Prone Y Raise Community

I have a mushroom neck and I'm trying to do some exercises, but how exactly should I position myself? I don't really feel it in my back. ㅜ

↳ 팔부털지마시고쇠골로움직이는걸느끼고난다음해보세요

Doing it on the bench increases mobility and is good.

Should the head be lifted off the ground?

↳ 목 나가요 띄면 안됩다