Energy of our body is concentrated all along our spine and located on several levels called Centres or Chakras. They are linked through energy canals (the same used in acupuncture).
As every source of energy, the Centres or Chakras vibrate to a particular frequency. This frequency, which is peculiar to the 7 chakras, is the one of color. These colors are the ones from the spectrum of the white light.Centres or Chakras are doors where energy goes in and out. So, there might have an excess or a lack. We can act on the corresponding chakra in order to regularize the problem.

Using chakras - Relaxation et getting fit again in the morning :
Lie down, close the eyes and make visual the first chakra like a little red circle, a red neither too vivid nor too pale. Set it just below sex organs. 1 to 2 minutes later, go to the second chakra and make it visual like a little orange circle. Set it at pubes level. Etc. ... Do the same for every chakra by respecting colors and their own place. To the seventh chakra and after making visual the purple circle, imagine a white beam of light which is going out of this chakra, it's getting wider and is getting back to cosmos merging with it in peace and fullness. Stay like this 1 to 2 minutes. Then make visual the beam still as white as ever which is going down again in the 7th chakra and which is disappearing in order to leave a place for the little purple circle, a purple neither too pale nor too vivid... Redo the visualization as it is in the beginning but this time from the 7th chakra to the 1st chakra.