I thought this was a very enlightened event, and of course I knew that David Letterman would never be completely comfortable retiring and doing nothing. At age 69, he is working with National Geographic. The former “Late Show” host will serve as a correspondent for an episode of the National Geographic Channel’s docuseries, “Years of Living Dangerously,” for its second season Oct. 30. The 69-year-old comedian traveled to India and met Prime Minister Narendra Modi to explore how one of the world’s largest populations is making the move from non-renewable energy to solar power. In his typical famous Letterman style, David explores solar and many other solutions to help offset the severity of human caused climate change.