Today, I walked to work and back. By the time I got to work, my muscles were saying, "Aww yeah. About time. Walking's fun! Let's do some more!" My lungs, on the other hand, were protesting, and evidently my face had gone an odd color. By the time I got home, I was ready to fall over. My muscles are content to keep going as long as they get enough to breathe. My cardiovascular system wants to know where all its oxygen has disappeared to.
I'm glad I don't have to be back at work until Thursday.