Need Quick Ways to Calm Down? Here are Some Tips!

does anyone have any surefire methods for calming down quickly when you get worked up or nervous, similar to how caffeine can give you more energy but in reverse? preferably something short acting like 10-20 minutes but also open to longer techniques for when I'm not in a time crunch and just need to relax for bed or to be able to study. I usually drink chai tea, which helps with headaches and sometimes calms me, but it also has caffeine, which ofc naturally excites you, and I have a heart condition where they're telling me to avoid it. I'm also not looking into drugs like cigarettes, but if there are any tame otc solutions, I might be open to them.