We typically think of stress, particularly stress at work or at home, as a bad thing, but stress itself is neither good nor bad. It depends.
Stress is often defined as a physiological and/or psychological reaction to something that is perceived to be threatening or taxing. We most often think of it in negative terms, but the truth is that stress can be either good or bad. For example, research has shown that small amounts of stress can be motivating. We can think of this sort of stress as a challenge.
Of course, taken to extremes (as with most things), stress can be bad and harmful. The largest harm is the relationship between negative stress, what might better be termed “distress,” and stress related illnesses, including elevated blood pressure, heart disease, and other so-called “stress-related illnesses” (e.g., migraines, ulcers, etc.). [See more about extremes here]