Stress is the response of your body and mind to demands being placed on you. Some stress can be helpful when it is manageable and feels proportional to the tasks or situations that need your attention. Too much stress, though, can take a real toll on your mental health and well-being.
Stress itself is not a mental illness. But when the stress keeps piling up and it starts to make you feel worse instead of motivating you, it can harm your mental health and well-being. Stress is a risk factor for someone who is already vulnerable to developing a mental illness. Stress can affect us physically, too.
As stress is based on the way you see a situation or event, things that cause stress are based on your own situation. If you feel well and in control, a problem may not seem very stressful. However, if you already feel stressed or overwhelmed, the same problem may add to your existing stress and feel very overwhelming.