This anxiety typically causes you to be tense, which can translate into a variety of body changes.
Some people get tension headaches, others experience gas and pain from an irritable colon.
Now let's say you break up with your boyfriend - or fail an exam. A likely result will be depression, and depression is known to cause all kinds of physical reactions, too, from difficulty breathing to chronic fatigue to insomnia. It's even quite common to be anxious and depressed at the same time, so that your feelings can be quite mixed. However, stress has been blamed wrongly for many conditions, probably because it's such a common experience that when we get sick, we can almost always remember a preceding stress. Yet many diseases or outbreaks are simply random events or bad luck.