Never underestimate the power of a Grandma ... especially if she goes to the gym. 

Shirley Rupp, 64 year old real estate agent and grandmother of 6 from Tuscon, AZ was leaving Subway when a thief tried to steal her purse ... tried.

Once the thief reached for her purse, she grabbed his jacket and tripped him. Stumbling, he managed to get up and run the other way dropping her wallet in the process.

"I work really hard for my money and you just can't let people take things away from you, so I didn't."

One thing that it is highly recommended is that you shouldn't try to fight off a robber if he is armed, but if you see the video, he didn't threaten Rupp at any time with any weapon. Rupp credits her time at the gym with being able to do what she did. Did ya' notice that she was even in her workout clothing?!

Wonder if the guy got some kind of bruise or something, can you imagine explaining to your girlfriend or friends what happened?! "Oh, I got my butt handed to me by a 64 year old woman." I've always said it, age has nothing to do with strength. So lesson be learned ... never underestimate those you think are weaker than you!!