Positive mood guards against getting colds

People with generally positive outlooks show greater resistance to developing colds than do individuals who rarely revel in upbeat feelings.

http://www.sciencenews.org/articles/20061216/fob2.asp

Cohen, S., et al. 2006. Positive emotional style predicts resistance to illness after experimental exposure to rhinovirus or influenza A virus. Psychosomatic Medicine 68(November/December):809-815. Abstract available at http://dx.doi.org/10.1097/01.psy.0000245867.92364.3c.