Scientists say they have found four keys to a longer life – or at least four healthy habits that can add more than a decade to a person's life.

Researchers tracked the lives of 20,000 people and found that those who practiced those habits lived an average of 14 years longer. Those findings of the study were recently published in the Public Library Science Medical Journal.

"For people who are not doing this, just a little bit of change will go a long way," Tara Miller, a registered dietitian, said.

Scientists identified the four common factors in the lifestyles of the long-lived study participants as:

• Not smoking.

• Eating lots of fruits and vegetables.

• Exercising regularly.

• Drinking alcohol only in moderation.

These healthy habits are not necessarily hard to pick up, but even practicing one of them can make a big difference, researchers said.

"You don't have to be a marathon runner in order to get the benefits of exercise," Miller said. "You don't have to be a strict vegetarian in order to reap the rewards of eating five fruits and vegetables a day.

"You just have to make small, incremental changes, and you will see a big effect by this."

Charles Hendrick said that although he already lives that kind of lifestyle, the news that it could add more than a decade to his lifespan was  encouraging.

"I do really watch what I eat. I exercise every other day," Hendrick said. "It's good to know that some of the habits I've accumulated through the years are, I guess, confirmed to help people live a greater quality of life and longer."