If you are stressed out, then you have stressors that you are not able to deal with. In other words, your stress is greater than your capacity to cope with it. We all have stressors- such as school, work, paying bills, relationships, just to name a few. When you are stressed out, the stressors don't need to be negative... they can be positive things, but when you are juggling multiple things, then your plate becomes full, and you are not able to handle anymore. So when you have a full plate, and you add more things to it, then you become stressed out and overwhelmed.
So if you are stressed out, then you need to take inventory of all the items in your life that takes your mental and physical energy. But you can't take inventory of the things that stress you out if you are currently stressed out. So you need to utilize relaxation techniques to calm down. Once you are calm, then you can begin to take inventory of the things that indeed stressed you out. When you are calm, stressful things that were not apparent to you earlier will become more clear.