This is a simple technique that helps with anxiety and can be done while sitting quietly in the car. It’s called Square or Box Breathing. Simply control your breathing by breathing in for the count of 4, hold for 4 seconds, breathe out for the count of 4, hold for 4 seconds and repeat for 4 to 6 cycles.
This is a great way to reduce anxiety by lowering the heart rate by working with the Vagus Nerve.
This is used by some law enforcement and military units during high pressure situations. If it’s good enough for them, you might want to give it a go too.