Another way to understand this is by understanding how a radio works. There is a tuner within the radio that when tuned to a particular station will only attract electromagnetic waves. Same is the case with us. Our attitudes, thoughts and energetic blueprints are what causes us to attract whatever we have in our life currently (either a lack of or a lot of.. whatever it may be).
A healthy fulfilled life begins with a healthy and fulfilled inner being. However, over time we do develop blockages in this mind-body-spirit continuity which slows and stops the natural flow of life and in many instances results in serious physical, mental, emotional and spiritual issues in life.
Since Reiki energy is from our higher consciousness, it knows exactly where to flow and hence there is very limited intervention required on behalf of the client and practitioner. Reiki healing is Curative and Preventative in nature (i.e. Curative - it will help heal existing issues at any level of our existence; Preventative – clients who treat themselves to Reiki regularly experience less and less of stressful situations, sickness and generally enjoy a much better level peace and happiness in their daily lives).
Please remember: Reiki is NOT a replacement for medical treatment but a complimentary addition to your physical treatments.