Stress refers to how the body responds to any number of physical or emotional stimuli (i.e., stressors). Effects of this response are sometimes perceptible-such as an increased heart rate, respiratory rate, sweating, skin problems, or tense muscles. Other changes, though common, are not perceptible: increased blood pressure, metabolism, and changes in circulating fats. Continued exposure to stressors, especially of a negative type, will often lead to mental and physical symptoms such as anxiety, depression, heart palpitations, and muscular aches and pains. Eventually, if one cannot find a way to effectively regulate stress, various physical and mental disorders may develop which may be serious enough to cause disability and even death.

There are many kinds of stressors: burnt toast, crying kids, arguments with co-workers, exercise, a passionate kiss, loud sounds, productive work, viruses, bacteria, overexposure to the sun, and grief are all examples of stressors. While some of these stressors could be considered good, pleasant and/or beneficial, they nevertheless cause a similar generalized response in the body. For example, what does an argument with your boss have in common with jogging? Since they are both stressors, they will each cause increased heart rate, increased blood pressure, increased respiratory rate and muscle tension. Though your perception of these two stressors might be different, your body's reaction to them is pretty much the same. Therefore, it is important to note that stress is cumulative. It doesn't make any difference whether the stressor is good or bad, if you have enough stressors occurring in your life at the same time, the body will suffer the "wear and tear"."

NOTE: the degree of stress which any stressor will cause is dependent on:

1.) the degree to which the stressor is present. In other words, the more of the stressor, the greater the stress it produces . So, for example, if a small headache causes some stress, a large headache will cause more stress. If a small argument causes a small amount of stress, a huge argument will cause more stress.

2.) how the stressor is perceived (different people will view stressors differently). As a result, one stressor might produce distress in one person and eustress in another.