skipping stars

I came so close to not going to the gym this morning. I wanted to just stay home from lab, too, because my cough/cold thing seemed to be worse and I was just feeling bad. My mum always claimed you should never exercise with a cold or something terrible would happen (the virus would get into your heart and kill you somehow? I don't remember), which was great when I was in high school and didn't want to do PE, but in hindsight might not necessarily be true. I've been trying to break myself of some of the irrational fears Mum passed down to me, and I really wanted my star, so I decided to risk it. I didn't work too hard at the gym (and I watched Dragon Tales, instead of reading), just in case. It turns out it's fine to continue exercising with a cold, but "exercise may cause a virus to invade the heart muscle or pericardium", according to one googled source, so Mum was half right. The consensus on google seems to be that symptoms above the neck are fine to ignore, but not below. I'm not sure if my cough is just rhinovirus-associated asthma, since it mostly goes away when I use my puffer, in which case it's probably fine to exercise, or if it really is due to an infection.

I'm wondering under what circumstances it would be appropriate to skip earning a star, anyway. If I really am sick and miss a day, does that mean no reward, or do I just have to make up a day at the end? Also, I'm travelling this week and won't be able to go to the gym. Is walking around sightseeing enough exercise to make up for that (I did do that once already)? Do I still have to do something productive? I'm not sure I can do that without inconveniencing my travelling companion. Can I just say those days don't count as part of the 30? I think I need someone to make up the rules for me, so I don't feel like I'm cheating.