One of my favorite indulgences, which I treat myself to a few times a year, is Real Simple magazine. I find it somewhat ironic that a magazine about simplicity has slick ads for so much stuff, but it's still a fun magazine to read.

This month, just in time for the cold and flu season, Real Simple featured an article on boosting your immunity. I expected tips on hand-washing, but the article made no mention of hygiene. It did, though, advise a low-fat, high protein diet and exercise as key factors in keeping your immune system strong. The article also had a few unexpected tips; citing studies on how singing while playing percussion instruments—or even petting your dog—elevates levels of antibodies.

The item in the list that caught my attention most: "Resolve to really relax." Apparently, stress suppresses circulation of immune cells, and elevates levels of cortisol in our bodies. Cortisol is a stress hormone that hampers white blood cell function (i.e., immunity). So taking time ...