Whoa. Check out this Yoga Granny. If this doesn't explain the benefits of yoga, there really isn't much I can do for you. She teaches up to 11 classes a week and maintains that killer hair-do.
If you want to look half as good as Yoga Granny, here is a great 20 minute yoga session for just about anyone. Sadie is a great teacher and really explains what a great workout this is. Now, bust out your yoga mat and get going!
Are you a yogi?