How often do you see a centenarian lady? And how will you react if you see her dressed in a Wonder Woman suit and walking up to cut up her 103rd birthday cake?

Meet Mary Cotter, a "real life Wonder Woman" as described by her friends.

She volunteers at the Montclair Senior Center in California and quite amazingly drives to and from the nursing home five days a week to help out — a job she has been doing for the last 25 years, The Mirror reports.

On Tuesday, October 13, she celebrated her 103rd birthday but this time it was slightly different.

Source: YouTube video screenshot

She put on a multi-coloured superhero suit and then joined the celebrations. The secret of her energy and stamina is "just keeping busy." In fact, the video of her birthday celebration has had more than 263,000 views since Tuesday.

She has won thousands of hearts with her superhero looks just like in 1930s, when Mary was a swimmer and helped lead her high school to victory in the state championships. Thirty years later, she was still swimming, but as a teacher. When she entered 90s, her love with the sea was still young, rescuing sea turtles.

Now, at 103, she is a Wonder Woman birthday heartthrob.

After all, as Mary says, age is "just a number."

Watch the lovely video here:

Feature image source: YouTube Video Screenshot