When Kristina Marcelli Sargent was nine years old, her father was struck by lightning. Immobilized by fear, she watched helplessly, wanting to help but unable to make herself move.

As she grew older, Kristina found herself freezing up over and over again in scary situations.

Then one day, a hike in the mountains changed everything.

On this episode, Kristina shares her story. It’s a story about how we react to fear — and about what happens when our natural responses don’t serve us.

In 2015, Sarah Allely was hit by a car while riding her bike. She suffered a mild traumatic brain injury, and in the ensuing weeks and months, she found it impossible to function normally.

Only one thing seemed to help: spending time in nature.

Now, several years later, Sarah has turned her experience into a documentary podcast series called Brain on Nature. On this episode, we share an excerpt from her show and talk with her about why nature is so important for the brain — for all of us.