They must be taught to recognize the consequences for the human body and to respect the needs of that body. This is for those born into the body. There are others, as mentioned, attaching as spirit attachments. This is very hard on the physical body, for they usually come in groups. Their energy field is NOT conducive to the human body and it is taxing to have them as spirit attachments.
Symptoms are similar to flu and to chronic fatigue and to fibromyalgia.
It's very important to surround ones body with gold light every day and to ask ones Higher Self and subconscious mind to keep the body free of all spirit attachments to the body. They feel they have a right to the earth as humans are about to destroy it - as they did theirs. They cannot just take it over, so they are seeking to influence and manipulate from the inside. They are very honest about this. They admit the Higher Selves don't like this and don't want this.