There is a very safe intermediate step to the mirror meditation. Sit in a comfortable position with a straight spine. Now,
start peeling layers. First, feel your skin, then go inside and feel your breath and realize these are not you. Now, look at your thoughts and realize that you can separate your thoughts from you. When for a brief time their is no thoughts, there is still you looking out. Keep feeling, sensing this you that is apart from everything else. Keep working on making this" I" the master that can be trained to observe your emotions, thoughts, and with more advanced development you can use this perspective to reduce pain to a substantial degree.
Do this for 30-90 days. While you are doing this learn a variety of grounding techniques, with sets of Tai Chi being numero uno.
After all of that, give the mirror meditation a shot.