There has not been a single experiment that has managed to find the "Life Force Energy" this site is trying to con people into improving. It is all a fantasy. Save your money, find a doctor if you are ill, a masseur if you are tense and a trained psycho-analyst if you feel the need. Don't choose this.
Reiki is magical thinking based fake treatment. There is no Ki. Life force concepts have been sought and despite the best efforts over hundreds of years, no evidence that it exists any more than do the four humours which pre-dated modern anatomy and medicine. If you have any kind of medical issue, see a real doctor with a real MD certification to find out what is really going on with your body. Don't be a sucker for charlatans like this.