Notice your breath - your breath is like your refuge, a safe place to return to. As you watch yourself breathe your mind begins to calm. Maybe not all the way but enough to not overreact to what is happening; enough to move to the next step.
Exercise: Sit comfortably in a chair. Place on hand on your belly. Place your mind right there also. Notice as you breathe in your belly expands; as you breathe out your belly falls. You can silently say to yourself 'expand' as you breathe in and 'fall' as you breathe out. You may prefer the pair 'in'/'out' instead. Simply become aware of movement in your body as you breathe in and as you breathe out. At anytime you may release your hand and continue noticing.
Notice sensations in your body - Emotions always show up somewhere in your body as sensations. For example, anxiety may be a buzzing in your arms or legs; love may be an open feeling in the heart; anger may be a tightening of the muscles in the arms or jaw; happiness may be a lightness to the muscles; and sadness maybe felt behind the eyes. Your job is to sit in a quiet place and notice where you feel sensations and what they are like. It may be different from what I listed. It’s a chance to get to know yourself and to identify the emotion. Identifying the emotion is half the battle to calming down. Plus it is a lot easier to soothe feelings in your body rather than soothing your crazy thoughts around what is happening.
Exercise: Sit in a quiet place and scan your body. Note where you feel something. It can be anything: tensing, tingling, buzzing, fast beating, shaking, etc. even numbness. It doesn’t matter what it is it’s the noticing that counts. It’s the realization of how a certain emotion shows up in your body at this time. Perhaps, say to yourself, “Oh this is how [fill in emotion] feels in my body.”
Remember everything is impermanent - As Buddha says, everything has a beginning, a time in existence, and an ending. You know you wont be feeling this emotion forever, right? Have you ever felt one emotion forever? As you watch the feelings in your body you can notice how they change. They may move to a new part of your body. They may change in intensity: may be decreasing, maybe increasing. But they are changing nonetheless. They may change flavor, too.
Exercise: As you first sit quietly bring your awareness right to a point of sensations. Be down at a detailed level. “Watch closely,” as Tich Naht Hanh says. Really notice. Maybe even notice your awareness traveling to a new location, a new sensation. Nothing is permanent. Each blip of sensation comes into existence, exists and goes away. A new one may show up but it, too, will change or go away. As your sensations change you can be reassured the emotions are coming out of existence, too. Also check-in every once in a while throughout the day. Where are the sensations now? How intense are they? Maybe they are not even there.
Find a way to soothe your body - When you discover how such and such an emotion feels in your body figure out what your body needs to feel better. In the case of buzzing in your muscles it may be take a run or doing a couple yoga poses. In the case of intensity behind the eyes it may mean let yourself cry. In the case of numbness it may mean taking a warm bath. Get to know what soothes your body. Don’t be afraid to experiment (with healthy choices, of course). This can happen anytime along this path not necessary as step #4.
Take time now to figure out what to do with this trigger- your mind is calm, your body feels good. Now you may figure out how a mature way to solve what ever is happening without reacting out of your emotion. It may mean talking. It may mean making a change to what you do. It may mean finding compassion for yourself or others. But remember it may also mean not doing anything.