Stress
Yes, your police officer career does come with some job stress. On any given day, you could be balancing a vehicle accident investigation, a lost child, a drunk and disorderly bar patron, and a four-time speeder who somehow still has his driver's license. You'll interact with other law enforcement agencies, perhaps a hospital, and a social service agency or two. While you're juggling all these cases, you must still adhere to proper police procedures and investigative protocols.
Simply put: Even though you're busy, you don't have a license to get sloppy.
You also have to find a way to handle the unpleasant parts of your job that could impact your overall quality of life. You can ask for help in processing an unsettling experience such as a nasty accident or particularly gory crime scene. Consider regular yoga, meditation, or some other spiritual practice to help keep yourself centered.
Also, look for community-based volunteer work that provides you with a sense of satisfaction. By taking care of yourself, and by contributing your talents to others, you can help manage your stress and keep yourself on an even keel.