Conversation so far:
What year did David Letterman left David Letterman's late show ?
CANNOTANSWER.
What did he do after he left the late show ?
following the end of Late Show Letterman has been seen occasionally at sports events such as the Indianapolis 500, during which he submitted to an interview with a local publication.
What did he said anything important in the interview ?
CANNOTANSWER.

Question: Did he do anything else apart from going to sport events ?
Self-contained rewrite: Besides going to sport events did David Letterman do anything else after he left the Late Show?