Variety has a really interesting article about the challenges of being both an actor and writer — true of several staff members on The Office:
[Paul] Lieberstein, who was strictly a writer before coming to “The Office,” finds his actor mind and producer mind in conflict in another way. [Steve] Carell, he explains, will pounce (in character) on any actor who fumbles an improv.
“He just devours you. If you take too long, he makes fun of you. If you say something that didn’t follow, he makes fun of you. It’s kind of amazing. While I’m watching it as a producer, when I’m not in the scene, it’s definitely something I’m hoping for.”
Link: Writer-performers stage balancing acts