I was able to make it to a step class twice this week, and there was no trouble with wheezing or shortness of breath. I go back to the Dr. next week. I think I'll ask her about using the inhaler half way through. I get frustrated because when I have trouble after 20 minutes (less than 10 minutes to go), and that's when I'm trying to push to get the last bit of mileage in.
I did get 2.6 miles last time in 30 minutes, with an incline of 3; my next goal is 2.75.