After studying 1,300 subjects from ages 21 to more than 100, the authors found that older people were more likely to have found their life's purpose, while younger people were more likely still searching. That's logical, given that wisdom is often born from experience. According to research by Stanford education professor William Damon, the author of "The Path to Purpose," only 20% of young adults have a fully realized sense of their life's meaning.And according to the new study, the presence of meaning in one's life showed a positive correlation to one's health, including improved cognitive function, while searching for it may have a slight negative effect. Mental and physical well-being was self-reported, and having a sense of purpose tended to peak around age 60, the study found.