Stress is typically caused by external events and situations that are painful or overwhelming, and that leave you feeling out of control.
External causes of stress:

Burnout on the job;
Financial problems;
Family illness and grief;
Separation or divorce.
Minor stresses range from having arguments to getting stuck in traffic jams.

Even a positive experience-marriage, a job promotion, or a new baby-can trigger stress. Internal causes of stress:Personal illness;

Loneliness;
Physical pain;
Emotional conflict;
Perfectionism;
The drive to excel.