103-year-old woman celebrates birthday by volunteering while dressed as Wonder Woman

MONTCLAIR, CA -- Mary Cotter is celebrating her 103rd birthday, but she's not one to sit by and mark the occasion.

She is up serving coffee, tea and water as a volunteer at the Montclair Senior Center. It's something she's been doing for 25 years.

"They call me the barmaid because I'm serving drinks," Cotter said.

Her Wonder Woman outfit was a fitting gift from her friends, who say she is a real life wonder woman.

Time and age has not slowed the centenarian down. She still lives alone and drives to and from the center five days a week -- rain or shine.

Cotter says the secret to her longevity has to do with her daily routine. And it's pretty obvious if you stop and watch her for a moment.

"Just keep busy I guess," she said with a shrug.

She's been busy for years. In 1930, she helped her high school win the state swim championship. She taught swimming to children into her 60s and helped rescue sea turtles well into her 90s.

While everyone is pretty amazed by her unstoppable energy at 103, only Cotter remains unfazed by her years.

She says, "I don't know, just another day went by."