"You got to have friends to make that day last long," sings Bette Midler.

Good friends may help your life last longer, too.

A recent study followed nearly 1,500 older people for 10 years. It found that those who had a large network of friends outlived those with fewer friends by more than 20%.

Why? Some think good friends keep you from doing things that are bad for you, like smoking and heavy drinking. Friends may also ward off depression, boost your self-esteem, and provide support.