You just don't have the energy to explain why you're sad. Or you don't want to hear yourself saying it over and over. Its easier to just say that you're tired..I do it all the time. It's my idle, I idle here in gloom, and I don't know how to change that, I don't know how to reprogram my personality to rest at a higher level. Walking really helps elevate my spirit. Things will take a nice change in 6 weeks. Dec 5 should be pretty exciting!