The process of Awakening involves healing on multiple levels, not in the least the burning up of Samskaras, the positive and negative impressions that reside in the body and our mental system. Today we may refer these collectively as "stress", the Samskaras are a form of memory that are best dealt with at their root cause. If we have suffered some trauma we tend to develop a work-around that enables us to get on with our lives, yet we are living a life that is still at effect of that trauma. Meditation is a positive way of removing the stress of life, it is something that we can do for ourselves on a daily basis that we can have confidence in as an overall healing process. Sometimes though we could use a little extra help by way of a healing intervention.
Successful healing from illness and disease or emotional trauma is ultimately is up to you. The outcome from healing sessions often depend on one's willingness to make positive lifestyle changes such as getting enough exercise and eating healthy food. Karma also plays a role, healing may take place instantly, over time, or seemingly not at all.
A "healer" is someone who helps facilitate the process of healing. The healer does not actually do anything the real doing is done on a much subtler level, the healer works from there simply coordinating a potential positive outcome.