Dick Van Dyke, the legendary American actor and comedian who starred in classics such as Mary Poppins and Chitty Chitty Bang Bang, turned 100 on December 13. The beloved actor credits his remarkable longevity to his positive outlook and never getting angry.

While longevity of course comes down to many factors – including genetics and lifestyle – there is some truth to Van Dyke’s claims.

Numerous studies have shown that keeping stress levels low and maintaining a positive, optimistic outlook are correlated with longevity.