Not so easy and takes some groundwork. Here’s what I recommend:
1. Think about the soles of your feet (if standing) or the backs of your thighs (if sitting). Turn your attention to where gravity meets your body. How are your feet on the ground? Is one foot cooler than the other? How are your toes feeling? Middle one crampy?
Do you like the feel of your shoes or socks or the floor? How might you describe it? Likewise, for the backs of your thighs. What part of you is in contact with the chair? Is the chair soft or hard? How warm or cool are your thighs? Notice everything. The more the better.
Neuroscience shows that we have very little time to do something different when the internal planets align and panic/rage attack looms. It’s a half second. Distracting yourself with perceiving your body in space and time will give you more time.
2. Practice “going to your feet” several times a day so that it feels familiar.
3. Even more effective at calming the nervous system is a body scan. Download one of the apps (Calm, Insight Timer) and search for a voice you like. A body scan starts at one end (toes) and moves through the body with images and reminders to unclench the muscles until you reach the top of your head. Do this twice a day. It will help you sleep.
What we want is for you to have access to a way to calm yourself in any situation. It’s better if you practice and it becomes like second nature. Many folks use breathing techniques and both of the meditation apps have breathing meditations too.