system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why doesn't your heart ever get tired?

Isn't it just another muscle? But it works all day every day for your entire life. So why doesn't it ever need a break?
gpt
Cardiac muscle is different than all the muscles that you can consciously control. It's evolved to work 24/7 throughout your life. It gets a little break in between beats, so it's not like it's constantly exerting force.