How people deal with risks is one of the most interesting aspects of the human condition. Perceptions of risk are complex, and people deal with risks in different, often irrational, ways. Young, healthy people consider themselves immortal and immune from long-term, degenerative diseases. As a consequence they engage in risky dietary and smoking behaviors that enhance the chances of such diseases in later life. People often react irrationally to safety measures and to environmental health threats. Some drivers and passengers continue to avoid using seat belts even though it is well known that car restraints are one of the cheapest and most effective ways to reduce injuries and fatalities.