Scientists have discovered 5 traits linked with a longer, happier life

To measure optimism in the most recent study, researchers asked participants to rank how much they agreed with the following two statements: 1) "I feel that life is full of opportunities," and 2) "I feel that the future looks good for me." Using those measures, roughly a quarter of participants were identified as optimistic.

In the past, researchers have noted links between optimism and good health, even when accounting for differences in people's socioeconomic status. A recent German study of roughly 2,500 people found that psychological resources like optimistic personal beliefs positively affected participants' health across incomes and education levels.

Under 21% of the people in the most recent study were identified as having grit or being determined, making it the rarest out of the 5 life skills outlined in the study.

For the most recent study, some 30% of participants were identified as being emotionally stable, or being able to remain calm under stress or optimistic in the face of a challenge.

Other research links this trait with other positive outcomes, like living a long time. The same 75-year study that linked conscientiousness with longevity also concluded that in women, emotional stability had the strongest links to a long life out of all the traits. Since the study was done by asking other people to evaluate participants' characteristics, it may also provide some insight into how different traits are seen as more valuable based only on gender.

To find out which participants had a strong sense of control, the most recent study asked them to say how strongly they agreed with this statement: “At home, I feel I have control over what happens in most situations.” Using this measurement, about 41% of participants were defined as having the trait, making it the most common of all 5 characteristics.

While the idea of control might seem like an odd one to be tied with success, the finding is bolstered by some other studies. A 2011 study of 1,000 children who were regularly evaluated from birth until age 32 suggested that self-control in childhood could predict, to some extent, everything from participants' physical health to their personal finances.

So there you have it — five traits linked with a long and happy life. All you have to do is cultivate them.