Jobs like running a studio that require tremendous energy are particularly hard to do past a certain age.Soccer players, for example, tend to be washed up around 30. There's now much discussion over whether 31-year-old David Beckham is too old to continue to play for England.
On the other hand, he has the kind of specialized skill that serves an old player well -- on free kicks, nobody can bend it like Beckham still can.
As you get older, you want to do a few things extraordinarily well because you won't be able to do everything well.
Steve Sailor