16 senior citizens who are having the time of their lives

REUTERS/Nacho Doce

In São Paulo, Brazil, a contestant dances next to relatives and friends during a beauty contest for elderly women held in honor of Mother's Day.

People are living longer than ever before.

A recent study from the Institute for Health Metrics and Evaluation found that global life expectancy for both men and women increased from 65.3 years in 1990 to 71.5 years in 2013.

Senior citizens with big personalities - for example, 87-year-old grandma Baddie Winkle, who's earned more than 1.6 million followers for her hilarious posts on Instagram - are slowly changing the stereotypes surrounding those over 60.

The United Nations has even designated a day in October to honor the older people who have made contributions to our world. Dubbed the "International Day of Older Persons," October 1 is a day when we "recognize that older persons are an enormous asset to society and make a significant contribution to global development," UN Secretary General Ban-Ki Moon writes.

The following senior citizens are definitely still living life to the fullest - following the famous quote attributed to Mark Twain: "Age is an issue of mind over matter. If you don't mind, it doesn't matter."

(Captions by Sarah Jacobs and Reuters)