One of the most common somatic symptoms for anyone experiencing some level of anxiety is muscle tension. Many people carry tension in their bodies, which often leads to tense shoulders, back, jaw and neck muscles. This can also manifest as clenched jaw and teeth grinding. Some people find success at reducing these symptoms with some sort of muscle relaxation therapy. Read the linked article for more on how muscle relaxation therapy works.
Another common somatic complaint is changes in the digestive system. Many people experience constipation or diarrhea, which can become uncomfortable and difficult to routinely deal with. Additionally, people with GAD often have changes in their appetite when stress increases, either eating more than normal or less. In many cases, people also experience nausea. All of these cause concern since it can take a direct toll on your physical health, and it also means your body is not functioning at optimal levels, which makes it harder to deal with stress.
Changes in Sleep
One of the largest complaints from people with GAD is difficulty sleeping. Insomnia can take a toll on your physical health and also leaves you short on mental resources to deal with stress. Many people will take some form of sleep aid, but these should be dealt with carefully since they can lead to psychological and sometimes physiological dependence. Another idea could be to try the Kripke sleep method, which I write about in the “How to Get More Sleep” article.
It is important to distinguish between GAD and panic disorder, which is characterized by panic attacks. Read this brief piece on the definition of a panic attack for more complete information. Essentially, the extreme and sudden onset of racing heart, numbness and unusual physical sensations are less likely for people with GAD, but many people with GAD also have panic disorder. About.com also has a Guide for Panic Disorder that is also worth reading if this captures your experience.