Isadore Rosenfeld, MD: You don't want to stop the clock, you want to move with the clock. Stopping the clock means no progress. It means no new information for yourself.You want to stop where you are now, you will not grow, and you continue to grow as long as you live. So it shouldn't be a matter of stopping the clock;it should be a matter of staying as fit as you can. Now, I said that I enjoy all these things, but you know I get up very early every morning and I do 45 minutes of exercise,of aerobic exercise and 15 minutes of anaerobic. I hate it. But I feel better after I've done it. Age is not a function of the calendarbut in order to make it work, you've got to do, you've got to cooperate. And cooperating means staying physically fit. I know men of 90 who are still chasing women.I mean they are chasing them downhill, but they're still chasing them.