What drives at least some of the health benefits goes beyond biology, Miller says. "It may have to do with the fact that when you're around people, you think, 'Oh, Martha has gone for her mammogram—that reminds me, I should, too.' "
Eager to please
People-pleasers—Type C's—are conforming, passive, and want to accommodate. That can be a good thing when it comes to patient compliance: They're more likely to take the right medicines in the right doses at the right times, for instance—once they see a doctor, that is. Making and following through on appointments can be challenging for Type C's, who tend to accept their fate as inevitable and fall readily into hopelessness and helplessness. That means others must push them to take care of themselves. "They may be less likely to maintain their health on their own," Belamaric says. "If they develop a problem, they may just complain about it, hoping somebody says, 'I have a good doctor, I'll make you an appointment.' " Some Type C's may be so mired that they don't seek medical attention—even when it's clearly necessary—and slough off preventive behaviors, like watching what they eat. "If they get a serious diagnosis, they may be passive, throw their hands up, and say, 'Well, there's nothing I can do about it, anyway. If it's my time, it's my time,' " Belamaric says.
Stressed and distressed
Type D's—D is for distressed—dwell on negative emotions and are afraid to express themselves in social situations. Compared to more optimistic sorts, a Type D may face three times the risk for future heart problems, according to a recent study in the journal Circulation: Cardiovascular Quality and Outcomes. Type D's also face a higher likelihood of compulsive overeating and substance abuse. "If you're a person who is prone to depression or anxiety, or if you're overly self-critical, there's more of a chance of turning to gratifying behavior to feel better," Miller says. ['Type D' Personality: How Distress Affects Your Health]
Optimistic versus pessimistic
Optimism "heavily influences physical and mental health," concluded a study published in May in the journal Clinical Practice & Epidemiology in Mental Health after researchers followed more than 500 males for 15 years. The rate of heart-related deaths was 50 percent lower among optimists than among pessimists. "Optimists have a higher quality of life, and they may be more resilient in the way they deal with stress," Miller says. "So if a problem comes along, they're able to handle it better, and they become less symptomatic." Glass-half-empty types harbor little hope for the future and tend more toward depression and anxiety disorders. But there's a catch for those at the extreme end of the optimism spectrum: They think of themselves as impervious to risks. Extreme optimists who smoke are the best examples. They believe they won't develop lung cancer. Why give up smoking to prevent a nonexistent risk?
The "self-healing personality"
That is the name Howard Friedman, a professor of psychology at the University of California-Riverside, attaches to people who are curious, secure, constructive, responsive, and conscientious. These traits translate to enthusiasm for life, emotional balance, and strong social relationships. "Positive emotions buffer hormonal responses to stress," says Friedman, who studies the relationship between personality and longevity. Self-healers, he says, "have healthier behavior patterns: more physical activity, a better diet, and less smoking and substance abuse."