Most people are familiar with the technique of taking deep inhalations to relax themselves, but one breathing technique is more effective at returning your body to a naturally calm and connected state.

Jane McGonigal:  A lot of people are very familiar with the technique of slow breathing or deep breathing to try to relax. But it turns out there’s a breathing technique that is more effective than that. I call it the power breath. And the way you do it is that you exhale for twice as long as you inhale. So you might inhale for a count of four and exhale for a count of eight. If you’re really kind of worked up maybe you can only inhale for two and out for four when you get started and then you kind of slow it down more as you go. Maybe inhale for eight and exhale for 16 once you get really good at it.

And it turns out that the reason why this works so effectively to calm yourself down is that it triggers a switch in your body’s nervous system from sympathetic nervous system state to parasympathetic. And parasympathetic is a nervous system state that’s associated with what they call "rest-and-digest." Some of that I think is for more like "fight-or-flight." So if you’re in a kind of fight-or-flight state, and you don’t want to be feeling that way, you can do this power breath: inhale for four, exhale for eight, and switch. Just you get to decide whether you’re in fight-or-flight or rest-and-digest.

Or another one is "connect." They call them "calm-and-connect" state. And this has been used effectively by people for all sorts of things for stopping a panic attack, for reducing the symptoms of a migraine, for dealing with muscle spasms or muscle cramps. Anything you can do to get your body to switch into that calm-connect, rest-and-digest state it can help with that.
There’s a simple reason why this form of breathing helps switch your body into that calm-and-connect, rest-and-digest state which is that when you are naturally calm, when you are naturally resting and not thinking about your breathing, that is the breathing pattern that your body adopts. So you’re basically fooling your brain and body into thinking that you’re already calm and connected, that you’re already at rest by breathing the way you would be breathing if you were naturally in a state of calm and connection.