Relaxing is great. You will almost always feel better if you're relaxed physically and mentally. This idea will only help for the physical component for the most part, but it may help you mentally to some extent too.

The idea is focusing your breathing towards a body part. If you believe you will feel more relaxed and you focus on the breathing, then you will feel much better, but if you sit back and try to analyze this one it's just not going to work.

To do this sit down in a comfortable position on the floor. The floor is not neccesary, but I find it to be best. Close your eyes and concentrate on taking slow deep breaths. Try to make them as even as possible. Now as you inhale, feel the energy of your breath diffuse into your torso. Feel the cleansing it brings to your body. Now focus on your leg. Feel the oxygen diffuse into your tissue. As you concentrate on each part of your body concentrate too on relaxation. As you inhale relax the part of the body you are focusing on. I usually feel that part of my body tingle. If you work on this continue for your whole body you will eventually be a big fleshy noodle of relaxation.