Is your glass half-empty or half-full? How you answer this age-old question about positive thinking may reflect your outlook on life, your attitude toward yourself, and whether you're optimistic or pessimistic — and it may even affect your health.

Indeed, some studies show that personality traits such as optimism and pessimism can affect many areas of your health and well-being. The positive thinking that usually comes with optimism is a key part of effective stress management. And effective stress management is associated with many health benefits. If you tend to be pessimistic, don't despair — you can learn positive thinking skills.