Karma is the energy, both positive and negative, that has build over time. A person may develop a disease as a way to facilitating a needed learning. It is not to be considered as punishment, but a learning process. Errors in life require redress, understanding or a change of attitude to heal them. Karma is generated by emotional attachments which are carried from one lifetime to the next, to resolve the situations and emotions. You did not inherit your Karma from someone else's bad decisions, you brought it on yourself. The first step towards healing your Karma is to take full responsibility for all of your actions that accrued over time. Doing so will allow you to begin moving forward and paying your Karma back by doing the opposite of what incurred your Karma. You must be aware of what you did specifically to incur Karma. That awareness allows the energy to shift and change state.  After you take responsibility for your actions, be specific about what your actions are... and do the exact opposite. You want to continue practicing and healing your Karma each and every day. Your Karma does not heal in a single step - it takes time (depends on how many problems we've created in this world).  Also if someone is healed by Reiki, or any other means, it's a fulfilling of their karma, or it would not have happened.