The physical act of moving forward. When you feel overwhelmed by an experience, take some form of physical action, like a walk. A walk is enough to get your blood flowing and move your mind and muscles, but it is also slow enough for you to be present and pay attention to what is around you. In front, to your side.
While hiking, I have learned to observe laterally, not my head but my eyes; your brain knows you are paying attention to your surroundings, so it keeps alert.
Pushing yourself across that threshold rewards you physically through achievement, but it also suppresses the fear centres of the brain because you are taking charge; it makes sense. These are hardwired features, not hacks that Mother Nature installed into us millions of years ago.
During a multi-day hike, your experience and exposure to outdoor morning and evening light anchor everything that happens between the top of your brain and the bottom of your feet.