Depends on a lot, first of all, why I am stressing?
If I'm stressing af because i need to do something, and I haven't done yet, I try to fix it and do it as fast as possible.
If I have stress because of something more emotional: music, fresh air outside (i love traveling, visiting unknown places helps me), long walks, talking to other people, joging, medicine helps (warm relaxing tea, herbs) and sleeping. Sometimes locking myself away from any social medias, including steam and shit, helps me as well. Watching motivational videos? Every situation has it's own metods.
So if you are stressing couse of exams, you need to understand why are you stressing. Are you not feeling ready for them? I would go study then.
If you studied enought, but you just have fear to fail, the hardest thing is to understand that what you are feeling is more than normal (you are human being with emotions), so i would offer exercising(joging, fast walking, just random exercises in home, weight lifting or some) and listening to music. Or talking with some friends, family, or if you dont have them, just people from the game.
Stress is a normal emotion as long as it wont control 100% of your mind and you can enjoy other things properly.
P.s. if you even fail, it's not end of the world. You can always fix things, redo it again next time. I know now, it seems exams is the most important thing, but trust me, it's not. Save your nerves and your health.