Straight definition of stress is – “a state of mental or emotional strain or suspense”. Or, as wikipedia describes: consequence of the failure of a human to appropriately respond to physical or emotional threats. It doesn’t actually matter if those threats are actual or just imagined dangers. In modern days, those threats usually arise from the outside world: workplace, family, community.
Stress is not necessarily a bad thing, it’s a response of your body, kind of a way of protecting you. While it doesn’t reach a certain point it can help you feel energetic, stay focused in your or, in emergency situations, give you extra strength and alertness.
Unfortunately, being in the highly stressful environments for a long time can cause serious damage to your health, mood and overall quality of life, because your body can’t understand if your stress is physical of psychological, so if you’re stressed about work situations, money problems or something like that, your body reacts physically: nerve system releases stress hormones, adrenaline, heart rate increases, blood pressure rises and while it is good thing for a short length of time it is unhealthy to be in such condition for a longer time.