Maybe it’s the heat these summer weeks have brought, or advancing years confirmed by yet another birthday. Somehow, I’ve toppled into a state of lethargy this month. I want to sit and read. Work crossword puzzles. Take a nap in the afternoon. It sounds lovely in theory, so why does this disturb me? I’m retired. Why do I feel guilty about this unproductive state? David Ekerdt, professor of gerontology in the Life Span Institute at the University of Kansas, suggests this guilt