It's simple and helpful.

http://www.heartmath.org/free-servic...nce-adult.html

(also: http://www.heartmath.org/free-servic...tion-tool.html )

The Heart Chakra is involved although they do not refer to "chakras" or energy centers in the text.

The HeartMath Institute also does very interesting research on the heart (being more than a pump organ).