Even small exertions, like walking up a flight of stairs, can leave many panting. As they try to get more oxygen, they breathe faster, and usually through their chest. “They think that breathing more is going to offset the lack of oxygen, so they get in this vicious cycle of hyperventilating, breathing into the chest, breathing through the mouth which, in the end, results in them getting even less oxygen,” says James Nestor, who wrote the New York Times best-selling book, Breath: The New Science of a Lost Art. “It off-gasses too much carbon dioxide in their bloodstreams. This causes vasoconstriction in their head, which is why they get so sick," adds Nestor. Instead, he recommends focusing on breathing deeply through the nose and belly.