There wasn't anything that could bring singer Pharrell Williams down in his hit song "Happy." Turns out he was on to something.
Being happy and optimistic can prolong your life, help you manage stress, lower your risk of death from cardiovascular disease and even help protect you from the common cold, according to the Mayo Clinic.
Not bad at all, especially as thinking positively doesn't cost you a thing.
There's no better time to try it out than on Positive Thinking Day, which is celebrated each September 13.
Click here for five expert tips to help you think yourself well.