When I started to watch this video of Kelly McGarry going downhill through the hilly city of Taxco, Mexico, I thought: "This is going to be bad." So I measured my heartbeat and then resumed the playback. When it was finished, four minutes later, my heart accelerated from 89 to 95 beats per minute.
Maybe I'm too impressionable. Or have terrible health. Or this iPhone heartbeat app is crap. It doesn't matter. At every turn I thought of me going down the same route and smashing my head against a concrete wall or stairs step. Listening to his heavy breathing in my headphones didn't help to keep me calm.