The force to cure illness

If the subconscient also answers, then even a slight touch of the Force can not only cure the particular illness but make that form or kind of illness practically impossible hereafter.
An untiring persistence is necessary; at first one may fail altogether or the symptoms increase, but gradually the control of the body or of a particular illness becomes stronger. Again, to cure an occasional attack of illness by inner means is comparatively easy, to make the body immune from it in future is more difficult.

Ref: Letters on Yoga – IV