You will get a lot of head aches, maybe stomach pains like your going to be sick. You will have trouble sleeping as things stressing you will be running though your head. So in other words, it makes life hard.
If you are stressed you are likely to do your work, If you were really relaxed and chilled back you might not be doing the best work that you can do. Stress helps us achieve our goals, without it we wouldn’t do anything.
When you are given way to much work than what you can cope with or if you've been given a deadline and there is way to much work to do, then this can cause stress on your body and mind. Conflict, bullying or even to little work can stress you out.