Stress related with mental problem.
.... wrong grammar;Stress is related with mental problems.
Stress related with mental problem. Stress is such as mental disorders. Mental disorders is a mental psychology make people depressed and physically. Characteristic of stress is beginning of depresses. Each person even has depressed.
This is not a proper introduction. You have gone completely out of topic. Look at your prompt;
Stress is now major problem in many countries around the world. What are some of the factor in modern society that cause this stress and how can we reduce it?
This does not ask you to keep defining stress. It asks you what causes stress and how that situation can be arrested. So, do not waste your entire introduction, just for telling the reader what stress is. You need to align your writing with what your prompt requests.