system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible to voluntarily control your own heartbeat like we can control our breathing?

Please no unverified anecdotes about yoga masters or shaolin monks.
gpt
You can temporarily lower your heartbeat doing vagal maneuvers. The best example is trying to force out a bowel movement. This actually causes many people to lose consciousness having an episode of vasovagal syncope, and is the reason why many older people pass out on the toilet.