People who feel cheerful, relaxed, energetic and satisfied with life are significantly less likely to have a heart attack, U.S. researchers say. \"If you are by nature a cheerful person and look on the bright side of things, you are more likely to be protected from cardiac events,\" study leader Lisa R. Yanek of the Johns Hopkins University School of Medicine said in a statement. \"A happier temperament has an actual effect on disease and you may be healthier as a result.\" However, Yanek warned that cheerful personalities are likely part of the temperament people are born with, not something that can be easily changed. Some have suggested it\'s possible that people lucky enough to have a happy trait might be more likely to take better care of themselves and have more energy to do so. However, Yanek said her research showed people with higher levels of well-being still had many risk factors for coronary disease, but had fewer serious heart events. Yanek and colleagues examined data from GeneSTAR, a 25-year Johns Hopkins project sponsored by the National Institutes of Health to determine the roots of heart disease. The study involved 1,483 healthy siblings of people who had coronary events before the age of 60 and who were tracked from five to 25 years. Siblings of people with early-onset coronary artery disease are twice as likely of developing it themselves, Yanek said. The study, published in the American Journal of Cardiology, found after an average 12-year follow-up, the researchers documented 208 coronary events -- heart attacks, sudden cardiac death, acute coronary syndrome, and the need for stents or bypass surgery -- in the sibling group. The researchers found that participants\' positive well-being was associated with a one-third reduction in coronary events; but among those at the highest risk for a coronary event, there was nearly a 50 percent reduction.