Dr. Volkow: For me it is really an extraordinary experience to go running. Some of the most exhilarating moments in a given day for me may be that morning, waking up in the morning and seeing the lights changing and that incredible sense of well-being that comes when you're running. I'm a very, very restless person. If I don't run in the morning, I will be jumpy all day long-- jumpy and anxious. Running allows me to calm myself down and to take things more slowly. In my work I am constantly faced with a wide variety of stressors and my ability to cope with stress is really helped by the physical activity. And I note that because when I'm... there's something that is really particularly problematic or that is taking an enormous amount of my emotional and intellectual energy, I go and I exercise very intensely, and then I feel calm. Right now, as a society, we have so many ways to be physically active. There are many exercises. So if you don't like to run, that's OK. You can actually go and take a dance class. You can go and do yoga. You can go join a gym. In my perspective, it does not matter what age you are. What is important is really to start. I would tell people don't shy away. If you are not good at something and you don't like it, then choose from the other wide variety of alternatives. The other thing that's fascinating about the body, even as it ages, is how if you start a program, no matter what your age, how rapidly you can become physically fit. And you can see results almost right away. And this can then motivate you to actually start to do these more regularly or to start increasing the intensity of what you are doing. So the body, itself, starts to respond. That's what I say to a person. Just try it. What do you have to lose?