A childhood belief about people

I used to believe that people can only faint once and if they fainted again, they'd actually die. So when i was about 8, my sister fainted on a car workshop because of sunstroke and i couldn't stop crying because i thought she was going to die the next time she fainted. When she woke up, i told her that "i'd take care of you so you won't die", she asked me what i meant and i told her. She laughed at me that she even forgotten about the heat and told me the real thing. I was in shock after she told me.