I Had A Question About A Person That Constantly Holds

I had a question about a person that constantly holds their breath unintentionally. Does constantly holding your breath like that cause any serious health problems? How does someone breath properly to prevent holding the chest so much to the point it feels like they're going to pass out? No health issues are in this person's medical history related to any breathing issues, but has had 2 near death experiences due to dehydration.