To arrive at a profound sense of physical relaxation and well being one can practice "progressive muscle relaxation", a technique for tensing and relaxing various muscle groups throughout the body. Often we do not even notice how tense our body has become simply because we get so used to feeling tense.
This audiofile will guide you through a progressive muscle relaxation exercise.
Practice progressive muscle relaxation on a daily basis, preferably twice a day, for two weeks.
Respect any physical limits you might encounter when tensing muscles. This is not the "no pain, no gain" approach. If you start to experience any muscle cramping or excessive discomfort you should forego tensing a particular muscle group.