Before going into any explanations or assumptions on why you are stressed, what stresses you, etc., we should all recognize that stress exists and that no-one can avoid feeling stressed at least once in a while. So the first piece of advice: just accept that stress exists and that it affects you. The more you will struggle to remove stress, the more burden on your mind, the more over-thinking about it, and the more miserable you may become.

the recommended strategy: Learn to minimize the adverse effect stress has on your life. Little by little, month by month, years by years, it will get easier and easier. Don't fight it: take the time to tame it. For 15 min. every day (ideally 45 min to be honest)
1.Find a calm place where you will not be disturbed
2. Sit, close your eyes and focus your attention on your breath (eventually count them 1 to 5, 1 to 5 again...)
3. If you become distracted (thoughts, emotions, whatever topic stresses you), acknowledge the situation, observe your reaction (muscle contraction? chocolate craving?), let the thought / emotion or sound fade and return your attention to your breath.
good luck