13 exercises to keep your legs strong at any age

From running to weight-lifting, there are a number of ways to put your legs into action.

But what if there were one simple workout that could target all those hard-to-reach parts of your legs - and you could do it at any age? Turns out there is!

As we did for our everyday stretching guide, Business Insider sought out expert advice from New York University physical therapy professor Marilyn Moffat, who also wrote the book "Age Defying Fitness." 

It's sure to get you sweating in no time - trust us. (Note: If you're having any unusual pain or problems with the exercises, please stop doing them and consult a physical therapist).