Most people are pretty reasonable about this kind of stuff, but scammers use low thresholds as an excuse not to work and hypochondriacs live in their own world.

In my case, the bike ride provides a useful reality check as I'm wondering how sick I could possibly be if I can handle that plus the workday. Usually, just getting your blood pumping will make you feel better. But when I was feeling totally beat less than a mile into the dog walk, I knew it was all over. I was hoping I might be able to rest up and get a short ride in this afternoon, but I can already tell that's not going to happen.