Mostly by the false beliefs instilled into us by western medicine and pharmaceuticals paired with, guilt, fear, anxiety, depression, ...wrong diet effects energetic "light and love" and out of balance chakra's.

Detachment, sometimes we get ill in order to learn we must detach.

Bad karma and mishandled emotions.

Negativity in any form caused illness. I am going through an illness right now that is caused by deep grief. I had it another time I was in deep grief.

Too much spirit?

None.

Fear. Faitless. Anger.

There are none. It is all physical. Even if it is psychological. The supernatural, spirits, God, etc., do not exist. So the only explanation can be physical.

Unbalanced humors, you need a good bloodletting.

Because all flesh is corrupted. Nothing good comes of the flesh but death.