I strongly believe that this is a skill they should teach in school (especially since school is a big source of stress for many). However, they don't and many people grow up without the knowledge or skills to effectively manage and identify the stress in their lives.
One of the most important (yet difficult) lessons we can learn is how to keep things in perspective. When something bad happens, or if things don't seem to be doing right, it's easy to fly off the handle, get angry, defensive, and even judgmental of others.
When learning how to manage stress, it's helpful to start by recognizing when you're about to be pushed past your tolerance point. Then, before that happens, take a step back and begin working on some stress management activities.
Another important component of managing stress is realizing that you have control over your reactions to the things that go on around you.
Stress is not caused by the events themselves. So recognizing that your beliefs about whatever is going on around you has the power to cause you stress or not. Tuning in to your belief system and your perceptions will help you recognize when you're having irrational thoughts that are causing you unnecessary stress.
If you can look within yourself to understand why you are experiencing stress, you can begin to eliminate and prevent some of your stress. In addition, having stress management strategies already in place will help you reduce the stress in your life once it occurs.