Yeah, I think we all have days like this. Sometimes it's just my lazy kicking in for one more round of "I don't wanna!", but sometimes it's truly my body saying "I simply can't."
Over time, I've gotten pretty good at being able to tell the difference, and I respect the "I simply can't" when I need to. Every time I do, I'm able to ratchet up my exercise the next day. I just needed rest.
The Beck Deck Crew!