Don't dwell on failures. Personal expectations are best when within reasonable limits. Learn to creatively utilize leisure activities. Some stress may require you to divert attention to tasks that require concentration. Other times require a brisk walk, swim, or other vigorous exercise.
Exercise appears to reduce some people's stress levels when regularly practiced.
Turn off worry. When you face problems that have no immediate solutions try to ignore them by immersing yourself in work, hobbies, and other interests. Not everything can be done perfectly. Some days it is best finish a task even though it is not perfectly in order to move on to other problems. Establish some personal time daily.