There's no slowing down for comedian Carlin

Though he's approaching 50 years in show business, 70 years on the planet and decades of heart trouble, George Carlin says this is no time to slow down.

"Pablo Casals, the cellist, you heard of him?" Carlin asked as he spoke briefly by phone recently before leaving for the U.S. Comedy Festival in Aspen, Colo., where he kicked off his 50th anniversary celebration this week.

"Pablo Casals was 94 and still practicing three hours a day and someone said to him, 'Why do you still practice three hours a day?' And he said, 'I'm beginning to notice some improvement."'

The comedian will celebrate his 70th birthday on May 12.