Recently I found an interesting interview to GM Jonathan Rowson
In it he explains how meditation had a profound impact on his life. Also he reveals that before every serious game he devotes 20 minutes to meditation. You can read more at the above mentioned website.
A couple of years ago I discovered a site where I was taught to meditate (and much more) for free http://www.aypsite.org/MainDirectory.html in a friendly non dogmatic way. I feel that meditation has improved meaningfully my life and my approach to chess as well.
Also, people who are interested in learning an inexpensive techinique leading to a stress-free life may give an eye to this link http://www.nsrusa.org/ A friend told me it works.