Step 1:
Sit upright or lie down in a quiet and comfortable location.

Step 2:
Imagine your body being bathed in blue light from the top of your head to the bottoms of your feet for four minutes.

Step 3:
Imagine green light entering through your navel and spreading out through your body. Take just one minute with the color green.

Step 4:
Inhale the color of your choice (utilize this starter color guide→colorguide), and imagine it spreading through your body.

Step 5:
Exhale and imagine the complementary color leaving your body (Complementary colors are found opposite one another on a color wheel. For instance, the complementary color for blue is orange, and the complementary color for green is red).

Step 6:
Take two minutes to mentally engulf your entire body in white light. Once you’re done, gently stretch your body, slowly “waking up” from your color meditation. This is a quick and free way to relieve tension and anxiety just about anywhere–even at your office.

Source: http://www.ehow.com/how_2031569_relieve-anxiety-through.html