We greatly overestimate our chances of being diagnosed with a lifethreatening illness like cancer or heart disease. Men and women, for example, rate their risk of getting prostate or breast cancer at about 40 percent. In reality, the risk is much lower - in the 10 percent range. Most people worry too much about getting a deadly disease or having a serious injury, and believe they have a 50 percent chance of having a heart attack. They actual risk is 40 percent for men and 10 percent for women. When asked about AIDS, most people consider their risk low - about 1.1 chances in 10. Actually, the risk is much lower, about one in 20, and even lower for people who do not engage in at-risk behavior such as needle sharing or unsafe sex. People also put their chances of being injured in a serious accident at 50 percent. The actual lifetime risk of this occurring is about five percent. We are living longer and healthier lives than ever before, but but greatly overestimate the dangers around us. Being cautious is great, as is living a healthy lifestyle, but it seems that too many of us worry needlessly about what the future might bring.