I get really stressed out and ****ty feeling if I eat too much pasta/rice/bread or too much sugar. A sandwich once a day, or some rice or noodles along with another dish is okay, but if I eat a big plate of spaghetti, or a half a US-style pizza, or a bunch of pastries, or too much rice, it turns the next 2 days to crap.
Aerobic exercise can be a big help.
Sleep is absolutely essential to keep stress under control. If I sleep less than 8 hrs/night for a few nights in a row, my ability to do useful work takes a dive, and I start getting preoccupied by all sorts of bull****. Also my immune system stops working properly, my hair gets greasy, etc.
I’m pretty good at staying calm under pressure, but also closely attuned to other people’s emotions. When someone near me is freaking out, especially if they get angry at me, I can handle it for a while, but if it lasts a couple hours I get burned out and need to go sit by myself for a few hours to recover. Being open with people about this is helpful, because then we can work on it together.
When immediately feeling stressed, taking a walk someplace quiet is pretty helpful for me.
I’m not big on meditation, but I have a couple friends who swear by it.
Hugs are great. (I know this is at least partly a culturally specific thing, YMMV.)
0.5–1 alcoholic drinks is a pretty effective anxiolytic. (More than one drink per hour is counterproductive for me though.) It won’t solve the root problem by itself, but sometimes calming down a bit right away is helpful for gaining some perspective or figuring out productive steps to attack whatever the real problem is.