One way to tell if acne is stress-related is to be aware of when breakouts tend to occur, and examine your stress levels from the preceeding week. If breakouts tend to match up with the times that your body is feeling stressed, there is probably a link. (If, however, you always tend to get acne on specific spots like the right side of your chin or your left cheek, that could actually be due to environmental factors like your cell phone resting on your face as you talk.)
You can practice stress management techniques to keep stress-related acne in check, and be sure to wash your face regularly as well. I also recommend exfoliating and even using a home microdermabrasion kit, which removes the top layer of skin and stimulates new, fresh skin to grow, but I'm not a dermatologist, so that recommendation is only a lay opinion. (See this article for more information on natural treatments for acne.)
As for the rest of your body, stress affects your body and health in many ways, from minor to major. It impacts virtually every system in your body, and even ages you prematurely. For more information on stress and health, I have these articles that can provide more details:
- Stress and Weight Gain: Can Stress Make You Fat?
- Psychosomatic Illness: Is it All In Your Head?
- Job Stress: A Risk Factor for Heart Disease, Diabetes, and Metabolic Syndrome
- The Stress and Health Section