No. Shielding is to protect yourself from unwanted negative energies that one has the potential to collect and come in contact with throughout the day.
This is partly why some people cleanse regularly, to get the unwanted energy off of them. Then, they do a sort of protective work.
Shielding is usually done with only visualization. But no, there is nothing wrong with adding words to go along with it.
Make a peace sign or something personal to you with your hand or hands. Where people can see or not. Its realy up to you and this can be done anywhere at any decibel, but aloud. Take a cleansing breathe and say, as above now so below. All around me protection grows. Them imagine a soft blue light surrounding you. I call it a prayer though. Once is usualy enough.
as said above shielding has nothing to do with physical harms. it doesn't protect you from diseases also. all it does is give you positive energy and shields you from negative energy and spirit
Actually, a lot of the Old Age traditions and beliefs have diseases and illnesses as coming from spirits, and some of the people who follow those traditions and beliefs today can and do treat diseases and illnesses in this way. It's not always necessarily so that it literally removes all traces of illness, more so that it allows one to better heal.
I've worked with spirits of illness and disease in order to curse a person before, and they were more than willing to help me out in making another person ill (I even took some of these outside of my own body).
I've also read some incredible stories of how positive thinking and positive energy has allowed people to overcome illnesses and diseases that otherwise kill many. It's all dependent on the disease/illness and how it can be fought. Never assume that metaphysical healing will 100% cure you, always be willing to do other treatments in order to assist with your condition. Even in ancient times, medicine and magic were mixed together in order to give the patient the best results possible.