Pushed too hard

My husband and I have been working on a playroom for our twins. Yesterday we started hanging drywall which is really heavy when you have to carry it up the stairs.
I was a little sore today but I figured it was no big deal. I got on the treadmill and pushed up the speed a little further than the fastest I had gone before. (hard to tell with my stupid console)
Apparently I pushed it too far. After 6.5 minutes I had gone .5 miles and started to have an asthma attack. So, I got off the treadmill and will try again tomorrow (or later) at a slower pace. Oops.