1. Make the room dark, or darker, and try to eliminate as much noise as possible. Lie down flat on your back. Use a pillow for comfort. Make sure no part of your body is strained or supporting weight. Close your eyes. Just pay attention to your breathing for a minute or two. Don't try to change it, just notice how it feels. Try to block out any ambient noise in your surroundings.
2. Practice breathing in and out of your nose. Take long breaths, not deep breaths. Try not to force it; you shouldn't hear your breath coming in or out. You're drawing slow breaths, not gulping it or blowing it out. Feel the rhythm of your breathing.
3. Allow your hands to lay by your side, but not touching your body. Have your palms down. Imagine that your hands are made of stone and are too heavy to move. With each exhalation, think the word "heavy" to mentally reinforce that your hands are motionless. Do this for the count of 10 slow, long breaths.
4. Next you're going to imagine that each muscle is releasing tension. Start with your feet, then lower leg, upper leg and so forth until you've gone up your entire body. As you start at your feet and move up your body, with each exhalation, imagine that heavy weighted sand bags are being lifted off your body. Imagine that they are being lifted away with each breath you exhale. As you move up your body you should feel a tension release.
5. The last step is to imagine you're standing in an open field on a nice warm day, with sun shinning and the sky completely blue. The field grass is green, and there are rolling hills spreading out into the horizon. Imagine you're standing there with a nice breeze and all of a sudden you are being lightly lifted into the air, and you begin to float through the sky.
As soon as you're ready, open your eyes and return to the world. You should feel a sense of relief and a shift in attitude. Do this whenever you need a stress reliever.