See Jane Run

I read an article on the New York Times' Web site today about women becoming faster runners as they get older. The article listed statistics from various races that showed that women in older age groups had faster times than women in the younger age groups.
When I go to the gym with my mom, who is 29 years my senior, she can work out for longer than I can and work harder than I can. Even during the summer, when we were spending equal amounts of time at the gym, I was still struggling more than she was, not to mention during yoga she is more flexible than I am. I remember looking over during one spinning class when I was out of breath and my mom was just biking along, not having any problems.
The article stated that older women may be faster because they have more committed goals, which was surprising to me, because younger women, in the 20-25 age group at least, are at the point in their lives when they are making goals and trying to achieve them in their professional and personal lives. Older women grew up during a time when track and cross-country teams were mostly men and they are only recently discovering what they're capable of.
That is similar to the situation my mom is in. Growing up she was never able to go to a gym or even work out every day so she is more motivated when she is at the gym now.