PeopleImages When people are under stress, they slump over as if they have the weight of the world on their shoulders. "Slumping restricts breathing and reduces blood and oxygen flow to the brain, adding to muscle tension and magnifying feelings of panic and helplessness," Dr. Cooper explains. Straightening your spine has just the opposite effect. It promotes circulation, increases oxygen levels in your blood and helps lessen muscle tension, all of which promote relaxation. The good news is, it only takes minutes to improve your posture .